Random Access Process in a Wireless Device

ABSTRACT

A wireless device initiates a first random access process on a first uplink carrier of a first cell in in response to receiving a first control command. The wireless device receives a second control command for transmission of a second random access preamble on a second uplink carrier of a second cell in the plurality of cells while the first random access process is on-going. The wireless device determines, employing a pre-defined rule, whether to continue with the first random access process and ignore the second control command; or to abort the first random access process and to transmit the second random access preamble.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/618,830, filed Apr. 1, 2012, entitled “Timing Management in WirelessNetworks,” and U.S. Provisional Application No. 61/654,900, filed Jun.3, 2012, entitled “Multiple Time Alignment Group Configuration,” whichare hereby incorporated by reference in its entirety.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Examples of several of the various embodiments of the present inventionare described herein with reference to the drawings, in which:

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present invention;

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers in a carrier group as per an aspect of anembodiment of the present invention;

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present invention;

FIG. 4 is a block diagram of a base station and a wireless device as peran aspect of an embodiment of the present invention;

FIG. 5 is a diagram depicting uplink transmission timing of one or morecells in a first timing advance group (TAG) and a second TAG as per anaspect of an embodiment of the present invention;

FIG. 6 is an example message flow in a random access process in asecondary TAG as per an aspect of an embodiment of the presentinvention;

FIG. 7 shows example TAG configurations as per an aspect of anembodiment of the present invention;

FIG. 8 is an example flow diagram illustrating a wireless device randomaccess process as per an aspect of an embodiment of the presentinvention;

FIG. 9 is an example flow diagram illustrating a base station randomaccess process as per an aspect of an embodiment of the presentinvention;

FIG. 10 is an example flow diagram illustrating a random access processin a wireless device as per an aspect of an embodiment of the presentinvention;

FIG. 11 is an example flow diagram illustrating a change in timingadvance group configuration as per an aspect of an embodiment of thepresent invention;

FIG. 12 is an example flow diagram illustrating random access process(s)as per an aspect of an embodiment of the present invention;

FIG. 13 is an example flow diagram illustrating random access process(s)as per an aspect of an embodiment of the present invention; and

FIG. 14 is an example flow diagram illustrating uplink signal timingadvance processing as per an aspect of an embodiment of the presentinvention.

DETAILED DESCRIPTION OF EMBODIMENTS

Example embodiments of the present invention enable operation ofmultiple timing advance groups. Embodiments of the technology disclosedherein may be employed in the technical field of multicarriercommunication systems. More particularly, the embodiments of thetechnology disclosed herein may relate to operation of multiple timingadvance groups.

Example embodiments of the invention may be implemented using variousphysical layer modulation and transmission mechanisms. Exampletransmission mechanisms may include, but are not limited to: CDMA (codedivision multiple access), OFDM (orthogonal frequency divisionmultiplexing), TDMA (time division multiple access), Wavelettechnologies, and/or the like. Hybrid transmission mechanisms such asTDMA/CDMA, and OFDM/CDMA may also be employed. Various modulationschemes may be applied for signal transmission in the physical layer.Examples of modulation schemes include, but are not limited to: phase,amplitude, code, a combination of these, and/or the like. An exampleradio transmission method may implement QAM (quadrature amplitudemodulation) using BPSK (binary phase shift keying), QPSK (quadraturephase shift keying), 16-QAM, 64-QAM, 256-QAM, and/or the like. Physicalradio transmission may be enhanced by dynamically or semi-dynamicallychanging the modulation and coding scheme depending on transmissionrequirements and radio conditions.

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present invention. As illustrated in thisexample, arrow(s) in the diagram may depict a subcarrier in amulticarrier OFDM system. The OFDM system may use technology such asOFDM technology, SC-OFDM (single carrier-OFDM) technology, or the like.For example, arrow 101 shows a subcarrier transmitting informationsymbols. FIG. 1 is for illustration purposes, and a typical multicarrierOFDM system may include more subcarriers in a carrier. For example, thenumber of subcarriers in a carrier may be in the range of 10 to 10,000subcarriers. FIG. 1 shows two guard bands 106 and 107 in a transmissionband. As illustrated in FIG. 1, guard band 106 is between subcarriers103 and subcarriers 104. The example set of subcarriers A 102 includessubcarriers 103 and subcarriers 104. FIG. 1 also illustrates an exampleset of subcarriers B 105. As illustrated, there is no guard band betweenany two subcarriers in the example set of subcarriers B 105. Carriers ina multicarrier OFDM communication system may be contiguous carriers,non-contiguous carriers, or a combination of both contiguous andnon-contiguous carriers.

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers as per an aspect of an embodiment of the presentinvention. A multicarrier OFDM communication system may include one ormore carriers, for example, ranging from 1 to 10 carriers. Carrier A 204and carrier B 205 may have the same or different timing structures.Although FIG. 2 shows two synchronized carriers, carrier A 204 andcarrier B 205 may or may not be synchronized with each other. Differentradio frame structures may be supported for FDD (frequency divisionduplex) and TDD (time division duplex) duplex mechanisms. FIG. 2 showsan example FDD frame timing. Downlink and uplink transmissions may beorganized into radio frames 201. In this example, radio frame durationis 10 msec. Other frame durations, for example, in the range of 1 to 100msec may also be supported. In this example, each 10 ms radio frame 201may be divided into ten equally sized sub-frames 202. Other subframedurations such as including 0.5 msec, 1 msec, 2 msec, and 5 msec mayalso be supported. Sub-frame(s) may consist of two or more slots 206.For the example of FDD, 10 subframes may be available for downlinktransmission and 10 subframes may be available for uplink transmissionsin each 10 ms interval. Uplink and downlink transmissions may beseparated in the frequency domain. Slot(s) may include a plurality ofOFDM symbols 203. The number of OFDM symbols 203 in a slot 206 maydepend on the cyclic prefix length and subcarrier spacing.

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present invention. The resource grid structure intime 304 and frequency 305 is illustrated in FIG. 3. The quantity ofdownlink subcarriers or resource blocks (RB) (in this example 6 to 100RBs) may depend, at least in part, on the downlink transmissionbandwidth 306 configured in the cell. The smallest radio resource unitmay be called a resource element (e.g. 301). Resource elements may begrouped into resource blocks (e.g. 302). Resource blocks may be groupedinto larger radio resources called Resource Block Groups (RBG) (e.g.303). The transmitted signal in slot 206 may be described by one orseveral resource grids of a plurality of subcarriers and a plurality ofOFDM symbols. Resource blocks may be used to describe the mapping ofcertain physical channels to resource elements. Other pre-definedgroupings of physical resource elements may be implemented in the systemdepending on the radio technology. For example, 24 subcarriers may begrouped as a radio block for a duration of 5 msec. In an illustrativeexample, a resource block may correspond to one slot in the time domainand 180 kHz in the frequency domain (for 15 KHz subcarrier bandwidth and12 subcarriers).

FIG. 4 is an example block diagram of a base station 401 and a wirelessdevice 406, as per an aspect of an embodiment of the present invention.A communication network 400 may include at least one base station 401and at least one wireless device 406. The base station 401 may includeat least one communication interface 402, at least one processor 403,and at least one set of program code instructions 405 stored innon-transitory memory 404 and executable by the at least one processor403. The wireless device 406 may include at least one communicationinterface 407, at least one processor 408, and at least one set ofprogram code instructions 410 stored in non-transitory memory 409 andexecutable by the at least one processor 408. Communication interface402 in base station 401 may be configured to engage in communicationwith communication interface 407 in wireless device 406 via acommunication path that includes at least one wireless link 411.Wireless link 411 may be a bi-directional link. Communication interface407 in wireless device 406 may also be configured to engage in acommunication with communication interface 402 in base station 401. Basestation 401 and wireless device 406 may be configured to send andreceive data over wireless link 411 using multiple frequency carriers.According to some of the various aspects of embodiments, transceiver(s)may be employed. A transceiver is a device that includes both atransmitter and receiver. Transceivers may be employed in devices suchas wireless devices, base stations, relay nodes, and/or the like.Example embodiments for radio technology implemented in communicationinterface 402, 407 and wireless link 411 are illustrated are FIG. 1,FIG. 2, and FIG. 3. and associated text.

According to some of the various aspects of embodiments, an LTE networkmay include many base stations, providing a user plane (PDCP: packetdata convergence protocol/RLC: radio link control/MAC: media accesscontrol/PHY: physical) and control plane (RRC: radio resource control)protocol terminations towards the wireless device. The base station(s)may be interconnected with other base station(s) by means of an X2interface. The base stations may also be connected by means of an S1interface to an EPC (Evolved Packet Core). For example, the basestations may be interconnected to the MME (Mobility Management Entity)by means of the S1-MME interface and to the Serving Gateway (S-GW) bymeans of the S1-U interface. The S1 interface may support a many-to-manyrelation between MMEs/Serving Gateways and base stations. A base stationmay include many sectors for example: 1, 2, 3, 4, or 6 sectors. A basestation may include many cells, for example, ranging from 1 to 50 cellsor more. A cell may be categorized, for example, as a primary cell orsecondary cell. When carrier aggregation is configured, a wirelessdevice may have one RRC connection with the network. At RRC connectionestablishment/re-establishment/handover, one serving cell may providethe NAS (non-access stratum) mobility information (e.g. TAI-trackingarea identifier), and at RRC connection re-establishment/handover, oneserving cell may provide the security input. This cell may be referredto as the Primary Cell (PCell). In the downlink, the carriercorresponding to the PCell may be the Downlink Primary Component Carrier(DL PCC), while in the uplink, it may be the Uplink Primary ComponentCarrier (UL PCC). Depending on wireless device capabilities, SecondaryCells (SCells) may be configured to form together with the PCell a setof serving cells. In the downlink, the carrier corresponding to an SCellmay be a Downlink Secondary Component Carrier (DL SCC), while in theuplink, it may be an Uplink Secondary Component Carrier (UL SCC). AnSCell may or may not have an uplink carrier.

A cell, comprising a downlink carrier and optionally an uplink carrier,is assigned a physical cell ID and a cell index. A carrier (downlink oruplink) belongs to only one cell, the cell ID or Cell index may alsoidentify the downlink carrier or uplink carrier of the cell (dependingon the context it is used). In the specification, cell ID may be equallyreferred to a carrier ID, and cell index may be referred to carrierindex. In implementation, the physical cell ID or cell index may beassigned to a cell. Cell ID may be determined using the synchronizationsignal transmitted on a downlink carrier. Cell index may be determinedusing RRC messages. For example, when the specification refers to afirst physical cell ID for a first downlink carrier, it may mean thefirst physical cell ID is for a cell comprising the first downlinkcarrier. The same concept may apply to, for example, carrier activation.When the specification indicates that a first carrier is activated, itequally means that the cell comprising the first carrier is activated.

Embodiments may be configured to operate as needed. The disclosedmechanism may be performed when certain criteria are met, for example,in wireless device, base station, radio environment, network, acombination of the above, and/or the like. Example criteria may bebased, at least in part, on for example, traffic load, initial systemset up, packet sizes, traffic characteristics, a combination of theabove, and/or the like. When the one or more criteria are met, theexample embodiments may be applied. Therefore, it may be possible toimplement example embodiments that selectively implement disclosedprotocols.

Example embodiments of the invention may enable operation of multipletiming advance groups. Other example embodiments may comprise anon-transitory tangible computer readable media comprising instructionsexecutable by one or more processors to cause operation of multipletiming advance groups. Yet other example embodiments may comprise anarticle of manufacture that comprises a non-transitory tangible computerreadable machine-accessible medium having instructions encoded thereonfor enabling programmable hardware to cause a device (e.g. wirelesscommunicator, UE, base station, etc.) to enable operation of multipletiming advance groups. The device may include processors, memory,interfaces, and/or the like. Other example embodiments may comprisecommunication networks comprising devices such as base stations,wireless devices (or user equipment: UE), servers, switches, antennas,and/or the like.

According to some of the various aspects of embodiments, serving cellshaving an uplink to which the same time alignment (TA) applies may begrouped in a TA group (TAG). Serving cells in one TAG may use the sametiming reference. For a given TAG, a user equipment (UE) may use onedownlink carrier as the timing reference at a given time. The UE may usea downlink carrier in a TAG as the timing reference for that TAG. For agiven TAG, a UE may synchronize uplink subframe and frame transmissiontiming of the uplink carriers belonging to the same TAG. According tosome of the various aspects of embodiments, serving cells having anuplink to which the same TA applies may correspond to the serving cellshosted by the same receiver. A TA group may comprise at least oneserving cell with a configured uplink. A UE supporting multiple TAs maysupport two or more TA groups. One TA group may contain the PCell andmay be called a primary TAG (pTAG). In a multiple TAG configuration, atleast one TA group may not contain the PCell and may be called asecondary TAG (sTAG). Carriers within the same TA group may use the sameTA value and the same timing reference.

FIG. 5 is a diagram depicting uplink transmission timing of one or morecells in a first timing advance group (TAG1) and a second TAG (TAG2) asper an aspect of an embodiment of the present invention. TAG1 mayinclude one or more cells, TAG2 may also include one or more cells. TAGtiming difference in FIG. 5 may be the difference in UE uplinktransmission timing for uplink carriers in TAG1 and TAG2. The timingdifference may range between, for example, sub micro-seconds to about 3omicro-seconds.

FIG. 7 shows example TAG configurations as per an aspect of anembodiment of the present invention. In Example 1, pTAG include PCell,and sTAG includes SCell1. In Example 2, pTAG includes PCell and SCell1,and sTAG includes SCell2 and SCell3. In Example 3, pTAG includes PCelland SCell1, and sTAG1 includes SCell2 and SCell3, and sTAG2 includesSCell4. Up to four TAGs may be supported and other example TAGconfigurations may also be provided. In many examples of thisdisclosure, example mechanisms are described for a pTAG and an sTAG. Theoperation with one example sTAG is described, and the same operation maybe applicable to other sTAGs. The example mechanisms may be applied toconfigurations with multiple sTAGs.

According to some of the various aspects of embodiments, TA maintenance,pathloss reference handling and the timing reference for pTAG may followLTE release 10 principles. The UE may need to measure downlink pathlossto calculate the uplink transmit power. The pathloss reference may beused for uplink power control and/or transmission of random accesspreamble(s). A UE may measure downlink pathloss using the signalsreceived on the pathloss reference cell. For SCell(s) in a pTAG, thechoice of pathloss reference for cells may be selected from and belimited to the following two options: a) the downlink SCell linked to anuplink SCell using the system information block 2 (SIB2), and b) thedownlink pCell. The pathloss reference for SCells in pTAG may beconfigurable using RRC message(s) as a part of SCell initialconfiguration and/or reconfiguration. According to some of the variousaspects of embodiments, PhysicalConfigDedicatedSCell information element(IE) of an SCell configuration may include the pathloss reference SCell(downlink carrier) for an SCell in pTAG. The downlink SCell linked to anuplink SCell using the system information block 2 (SIB2) may be referredto as the SIB2 linked downlink of the SCell. Different TAGs may operatein different bands. For an uplink carrier in an sTAG, the pathlossreference may be only configurable to the downlink SCell linked to anuplink SCell using the system information block 2 (SIB2) of the SCell.

To obtain initial uplink (UL) time alignment for an sTAG, eNB mayinitiate an RA procedure. In an sTAG, a UE may use one of any activatedSCells from this sTAG as a timing reference cell. In an exampleembodiment, the timing reference for SCells in an sTAG may be the SIB2linked downlink of the SCell on which the preamble for the latest RAprocedure was sent. There may be one timing reference and one timealignment timer (TAT) per TA group. TAT for TAGs may be configured withdifferent values. When the TAT associated with the pTAG expires: allTATs may be considered as expired, the UE may flush all HARQ buffers ofall serving cells, the UE may clear any configured downlinkassignment/uplink grants, and the RRC in the UE may release PUCCH/SRSfor all configured serving cells. When the pTAG TAT is not running, ansTAG TAT may not be running. When the TAT associated with sTAG expires:a) SRS transmissions may be stopped on the corresponding SCells, b) SRSRRC configuration may be released, c) CSI reporting configuration forthe corresponding SCells may be maintained, and/or d) the MAC in the UEmay flush the uplink HARQ buffers of the corresponding SCells.

Upon deactivation of the last SCell in an sTAG, the UE may not stop TATof the sTAG. In an implementation, upon removal of the last SCell in ansTAG, TAT of the TA group may not be running. RA procedures in parallelmay not be supported for a UE. If a new RA procedure is requested(either by UE or network) while another RA procedure is already ongoing,it may be up to the UE implementation whether to continue with theongoing procedure or start with the new procedure. The eNB may initiatethe RA procedure via a PDCCH order for an activated SCell. This PDCCHorder may be sent on the scheduling cell of this SCell. When crosscarrier scheduling is configured for a cell, the scheduling cell may bedifferent than the cell that is employed for preamble transmission, andthe PDCCH order may include the SCell index. At least a non-contentionbased RA procedure may be supported for SCell(s) assigned to sTAG(s).

FIG. 6 is an example message flow in a random access process in asecondary TAG as per an aspect of an embodiment of the presentinvention. eNB transmits an activation command 600 to activate an SCell.A preamble 602 (Msg1) may be sent by a UE in response to the PDCCH order601 on an SCell belonging to an sTAG. In an example embodiment, preambletransmission for SCells may be controlled by the network using PDCCHformat 1A. Msg2 message 603 (RAR: random access response) in response tothe preamble transmission on SCell may be addressed to RA-RNTI in PCellcommon search space (CSS). Uplink packets 604 may be transmitted on theSCell, in which the preamble was transmitted.

According to some of the various aspects of embodiments, initial timingalignment may be achieved through a random access procedure. This mayinvolve the UE transmitting a random access preamble and the eNBresponding with an initial TA command NTA (amount of timing advance)within the random access response window. The start of the random accesspreamble may be aligned with the start of the corresponding uplinksubframe at the UE assuming NTA=0. The eNB may estimate the uplinktiming from the random access preamble transmitted by the UE. The TAcommand may be derived by the eNB based on the estimation of thedifference between the desired UL timing and the actual UL timing. TheUE may determine the initial uplink transmission timing relative to thecorresponding downlink of the sTAG on which the preamble is transmitted.

A base station may communicate with a mix of wireless devices. Wirelessdevices may support multiple technologies, or multiple releases of thesame technology, have some specific capability depending on the wirelessdevice category and/or capability. A base station may comprise multiplesectors. When this disclosure refers to a base station communicatingwith a plurality of wireless devices, this disclosure may refer to asubset of the total wireless devices in the coverage area. Thisdisclosure may refer to, for example, a plurality of wireless devices ofa given LTE release with a given capability and in a given sector of thebase station. The plurality of wireless devices in this disclosure mayrefer to a selected plurality of wireless devices, and/or a subset oftotal wireless devices in the coverage area, which perform according tothe disclosed methods, and/or the like. There may be many wirelessdevices in the coverage area that may not comply with the disclosedmethods, for example, because those wireless devices perform based onolder releases of LTE technology. A time alignment command MAC controlelement may be a unicast MAC command transmitted to a wireless device.

According to some of the various aspects of various embodiments, thebase station or wireless device may group cells into a plurality of cellgroups. The term “cell group” may refer to a timing advance group (TAG)or a timing alignment group or a time alignment group. Time alignmentcommand may also be referred to timing advance command. A cell group mayinclude at least one cell. A MAC TA command may correspond to a TAG. Acell group may explicitly or implicitly be identified by a TAG index.Cells in the same band may belong to the same cell group. A first cell'sframe timing may be tied to a second cell's frame timing in a TAG. Whena time alignment command is received for the TAG, the frame timing ofboth first cell and second cell may be adjusted. Base station(s) mayprovide TAG configuration information to the wireless device(s) by RRCconfiguration message(s).

The mapping of a serving cell to a TAG may be configured by the servingeNB with RRC signaling. The mechanism for TAG configuration andreconfiguration may be based on RRC signaling. According to some of thevarious aspects of embodiments, when an eNB performs SCell additionconfiguration, the related TAG configuration may be configured for theSCell. In an example embodiment, eNB may modify the TAG configuration ofan SCell by removing (releasing) the SCell and adding (configuring) anew SCell (with the same physical cell ID and frequency) with an updatedTAG ID. The new SCell with the updated TAG ID may be initially inactivesubsequent to being assigned the updated TAG ID. eNB may activate theupdated new SCell and then start scheduling packets on the activatedSCell. In an example implementation, it may not be possible to changethe TAG associated with an SCell, but rather, the SCell may need to beremoved and a new SCell may need to be added with another TAG. Forexample if there is a need to move an SCell from an sTAG to a pTAG, atleast one RRC message, for example, at least one RRC reconfigurationmessage, may be send to the UE to reconfigure TAG configurations byreleasing the SCell and then configuring the SCell as a part of pTAG(when an SCell is added/configured without a TAG index, the SCell isexplicitly assigned to pTAG). The PCell may not change its TA group andmay always be a member of the pTAG.

An eNB may perform initial configuration based on initial configurationparameters received from a network node (for example a managementplatform), an initial eNB configuration, a UE location, a UE type, UECSI feedback, UE uplink transmissions (for example, data, SRS, and/orthe like), a combination of the above, and/or the like. For example,initial configuration may be based on UE channel state measurements orreceived signal timing. For example, depending on the signal strengthreceived from a UE on various SCells downlink carrier or bydetermination of UE being in a repeater coverage area, or a combinationof both, an eNB may determine the initial configuration of sTAGs andmembership of SCells to sTAGs.

In an example implementation, the TA value of a serving cell may change,for example due to UE's mobility from a macro-cell to a repeater or anRRH (remote radio head) coverage area. The signal delay for that SCellmay become different from the original value and different from otherserving cells in the same TAG. In this scenario, eNB may re-configurethis TA-changed serving cell to another existing TAG. Or alternatively,the eNB may create a new TAG for the SCell based on the updated TAvalue. The TA value may be derived, for example, through eNBmeasurement(s) of signal reception timing, a RA mechanism, or otherstandard or proprietary processes. An eNB may realize that the TA valueof a serving cell is no longer consistent with its current TAG. Theremay be many other scenarios which require eNB to reconfigure TAGs.During reconfiguration, the eNB may need to move the reference SCellbelonging to an sTAG to another TAG. In this scenario, the sTAG wouldrequire a new reference SCell. In an example embodiment, the UE mayselect an active SCell in the sTAG as the reference timing SCell.

eNB may consider UE's capability in configuring multiple TAGs for a UE.UE may be configured with a configuration that is compatible with UEcapability. Multiple TAG capability may be an optional feature and perband combination Multiple TAG capability may be introduced. UE maytransmit its multiple TAG capability to eNB via an RRC message and eNBmay consider UE capability in configuring TAG configuration(s).

The purpose of an RRC connection reconfiguration procedure may be tomodify an RRC connection, (e.g. to establish, modify and/or release RBs,to perform handover, to setup, modify, and/or release measurements, toadd, modify, and/or release SCells). If the received RRC ConnectionReconfiguration message includes the sCellToReleaseList, the UE mayperform an SCell release. If the received RRC Connection Reconfigurationmessage includes the sCellToAddModList, the UE may perform SCelladditions or modification.

The parameters related to SCell random access channel may be common toall UEs. For example PRACH configuration (RACH resources, configurationparameters, RAR window) for the SCell may be common to UEs. RACHresource parameters may include prach-configuration index, and/orprach-frequency offset. SCell RACH common configuration parameters mayalso include power: power ramping parameter(s) for preambletransmission; and max number of preamble transmission parameter. It ismore efficient to use common parameters for RACH configuration, sincedifferent UEs will share the same random access channel.

eNB may transmit at least one RRC message to configure PCell, SCell(s)and RACH, and TAG configuration parameters. MAC-MainConfig may include atimeAlignmentTimerDedicated IE to indicate time alignment timer valuefor the pTAG. MAC-MainConfig may further include an IE including asequence of at least one (sTAG ID, and TAT value) to configure timealignment timer values for sTAGs. In an example, a first RRC message mayconfigure TAT value for pTAG, a second RRC message may configure TATvalue for sTAG1, and a third RRC message may configure TAT value forsTAG2. There is no need to include all the TAT configurations in asingle RRC message. In an example embodiment they may be included in oneor two RRC messages. The IE including a sequence of at least one (sTAGID, and TAT) value may also be used to update the TAT value of anexisting sTAG to an updated TAT value. The at least one RRC message mayalso include sCellToAddModList including at least one SCellconfiguration parameters. The radioResourceConfigDedicatedSCell(dedicated radio configuration IEs) in sCellToAddModList may include anSCell MAC configuration comprising TAG ID for the corresponding SCelladded or modified. The radioResourceConfigDedicatedSCell may alsoinclude pathloss reference configuration for an SCell. If TAG ID is notincluded in SCell configuration, the SCell is assigned to the pTAG. Inother word, a TAG ID may not be included inradioResourceConfigDedicatedSCell for SCells assigned to pTAG. TheradioResourceConfigCommonSCell (common radio configuration IEs) insCellToAddModList may include RACH resource configuration parameters,preamble transmission power control parameters, and other preambletransmission parameter(s). At the least one RRC message configuresPCell, SCell, RACH resources, and/or SRS transmissions and may assigneach SCell to a TAG (implicitly for pTAG or explicitly for sTAG). PCellis always assigned to the pTAG.

According to some of the various aspects of embodiments, a base stationmay transmit at least one control message to a wireless device in aplurality of wireless devices. The at least one control message is forexample, RRC connection reconfiguration message, RRC connectionestablishment message, RRC connection re-establishment message, and/orother control messages configuring or reconfiguring radio interface,and/or the like. The at least one control message may be configured tocause, in the wireless device, configuration of at least: I) a pluralityof cells. Each cell may comprise a downlink carrier and zero or oneuplink carrier. The configuration may assign a cell group index to acell in the plurality of cells. The cell group index may identify one ofa plurality of cell groups. A cell group in the plurality of cell groupsmay comprise a subset of the plurality of cells. The subset may comprisea reference cell with a reference downlink carrier and a referenceuplink carrier. Uplink transmissions by the wireless device in the cellgroup may employ the reference cell (the primary cell in pTAG and asecondary cell in an sTAG). The wireless device may employ asynchronization signal transmitted on the reference downlink carrier astiming reference to determine a timing of the uplink transmissions. Thesynchronization signal for example may be a) primary/secondarysynchronization signal, b) reference signal(s), and/or c) a combinationof a) and b). II) a time alignment timer for each cell group in theplurality of cell groups; and/or III) an activation timer for eachconfigured secondary cell.

The base station may transmit a plurality of timing advance commands.Each timing advance command may comprise: a time adjustment value, and acell group index. A time alignment timer may start or may restart whenthe wireless device receives a timing advance command to adjust uplinktransmission timing on a cell group identified by the cell group index.A cell group may be considered out-of-sync, by the wireless device, whenthe associated time alignment timer expires or is not running. The cellgroup may be considered in-sync when the associated time alignment timeris running.

The timing advance command may causes substantial alignment of receptiontiming of uplink signals in frames and subframes of all activated uplinkcarriers in the cell group at the base station. The time alignment timervalue may be configured as one of a finite set of predetermined values.For example, the finite set of predetermined values may be eight. Eachtime alignment timer value may be encoded employing three bits. TAG TATmay be a dedicated time alignment timer value and is transmitted by thebase station to the wireless device. TAG TAT may be configured to causeconfiguration of time alignment timer value for each time alignmentgroup. The IE TAG TAT may be used to control how long the UE isconsidered uplink time aligned. It corresponds to the timer for timealignment for each cell group. Its value may be in number of sub-frames.For example, value sf500 corresponds to 500 sub-frames, sf750corresponds to 750 sub-frames and so on. An uplink time alignment iscommon for all serving cells belonging to the same cell group. In anexample embodiment, the IE TAG TAT may be defined as: TAGTAT::=SEQUENCE{TAG ID, ENUMERATED {sf500, sf750, sf1280, sf1920, sf2560,sf5120, sf10240, infinity}}. Time alignment timer for pTAG may beindicated in a separate IE and may not be included in the sequence.

In an example, TimeAlignmentTimerDedicated IE may be sf500, and then TAGTAT may be {1, sf500; 2, sf2560; 3, sf500}. In the example, timealignment timer for the pTAG is configured separately and is notincluded in the sequence. In the examples, TAG0 (pTAG) time alignmenttimer value is 500 subframes (500 m-sec), TAG1 (sTAG) time alignmenttimer value is 500 subframes, TAG2 time alignment timer value is 2560subframes, and TAG3 time alignment timer value is 500 subframes. This isfor example purposes only. In this example a TAG may take one of 8predefined values. In a different embodiment, the enumerated valuescould take other values.

FIG. 6 is an example message flow in a random access process in a TAG asper an aspect of an embodiment. A preamble 602 may be sent by a UE inresponse to the PDCCH order 601 on an SCell belonging to an sTAG.Preamble transmission for SCells may be controlled by the network usingPDCCH format 1A (control command). Msg2 message 603 (also called arandom access response: RAR) in response to the preamble transmission onSCell may be addressed to RA-RNTI in PCell common search space (CSS).Uplink packets 604 may be transmitted on the SCell in which the preamblewas transmitted.

In one of the various implementations, RAR may include an uplink grant.In LTE release 10, a RAR uplink grant may be for the primary cell bydefault. In order to allow more flexibility, the uplink grant in RAR inmultiple TAG configuration may need to allow transmission of an uplinkgrant for a secondary cell. In one embodiment, this could beaccomplished by including a cell index in the RAR uplink grant. In orderto allow more flexibility in the uplink grant, and at the same timereduce overhead, a new mechanism may be implemented. Including an SCellindex in a RAR uplink grant may increase signaling overhead. The SCellindex in the uplink grant may not be transmitted in the uplink grant inRAR and the uplink grant contained in the RAR may be applicable to thecell where the preamble was sent by default. This may reduce thesignaling overhead.

In LTE release 10, the timing advance command (TAC) in a RAR is appliedto the pCell and to the sCells synchronized with the pCell. In order toallow more flexibility, the TAC in a RAR in a multiple TAG configurationmay need to be applied to secondary cell groups. In one embodiment, thiscould be accomplished by including a cell group index in the RAR TAC. Inorder to allow more flexibility in TAC, and at the same time reduceoverhead, a new mechanism may be implemented. Including a cell groupindex in a RAR TAC may increase signaling overhead. The cell group indexin the TAC may not be transmitted in the TAC in a RAR. The TAC containedin the RAR may be applicable to the cell group where the preamble wassent by default. This may reduce the signaling overhead. For example, ifthe random access preamble is sent on a first secondary cell of a firstsecondary cell group. The TAC in a RAR may be applicable to the firstsecondary cell group. The wireless device may apply the TAC in a RAR toall activated secondary cells in the first secondary cell group.

According to some of the various aspects of embodiments, a RAPID may beincluded in Msg2 603 to address possible preamble misdetection by theeNB. UE may compare the RAPID in Msg2 603 with the transmitted preambleID to verify the validity of the Msg2 603 and to verify possiblepreamble misdetection by the eNB. A RAR may always be transmitted on aPCell independent of the cell used for preamble transmission (sCell orpCell). UE may monitor and receive a RAR with a specific RA-RNTIassociated with the random access channel used for random accesspreamble transmission. The specific RA-RNTI may be defined based on thesubframe (t_id) and frequency index of the physical random accesschannel (f_id) that is used for random access preamble transmission.

If no Random Access Response is received within the RA Response window,or if none of all received Random Access Responses contain a RandomAccess Preamble identifier corresponding to the transmitted RandomAccess Preamble, the Random Access Response reception may be considerednot successful and the UE may increment thePREAMBLE_TRANSMISSION_COUNTER by 1. If thePREAMBLE_TRANSMISSION_COUNTER=preambleTransMax+1 and if the RandomAccess Preamble is transmitted on the PCell, the UE may indicate aRandom Access problem to upper layers. If thePREAMBLE_TRANSMISSION_COUNTER=preambleTransMax+1 and if the RandomAccess Preamble is transmitted on an SCell, the UE may consider theRandom Access procedure unsuccessfully completed.

FIG. 8 is an example flow diagram illustrating a wireless device randomaccess process as per an aspect of an embodiment. According to some ofthe various aspects of embodiments, a wireless device may be configuredto communicate employing a plurality of cells. The wireless device mayreceive at least one control message from a base station at block 800.The at least one control message may cause in the wireless device:configuration of a primary cell and at least one secondary cell, and/orassignment of each of the at least one secondary cell to a cell group.The assignment may be done implicitly or explicitly as described in thisdisclosure. A cell group may be in a plurality of cell groups. Theplurality of cell groups may comprise a primary cell group and at leastone secondary cell group.

According to some of the various aspects of embodiments, the primarycell group may comprise a first subset of the plurality of cells. Thefirst subset may comprise the primary cell. Uplink transmissions by thewireless device in the primary cell group may employ the primary cell asa primary timing reference cell. Uplink transmissions by the wirelessdevice in the primary cell group may employ a first synchronizationsignal transmitted on the primary cell as a primary timing reference. Asecondary cell group in the at least one secondary cell group maycomprise a second subset of the at least one secondary cell. Uplinktransmissions in the secondary cell group may employ an activatedsecondary cell as a secondary timing reference cell. Uplinktransmissions in the secondary cell group may employ a secondsynchronization signal on the activated secondary cell in the secondarycell group as a secondary timing reference.

According to some of the various aspects of embodiments, the wirelessdevice may transmit a random access preamble on random access resourcesof a first secondary cell in the at least one secondary cell at block802. The wireless device may transmit the random access preamble inresponse to receiving a control command (PDCCH order) from the basestation. The first secondary cell may be the same as the activatedsecondary cell or may be a different secondary cell in the secondarycell group.

The wireless device may receive a random access response (at block 805)on the primary cell of the primary cell group in response to the randomaccess preamble transmission. The random access response may comprise: atiming advance command, an uplink grant, and/or a preamble identifieridentifying the random access preamble. The wireless device may applythe timing advance command only to uplink transmission timing of a firstsecondary cell group comprising the first secondary cell at block 807.The random access response does not comprise an index identifying thefirst secondary cell group. The wireless device applies the TAC to thecell group comprising the cell that was employed for preambletransmission. This may reduce signaling overhead by eliminatinginclusion of cell group index in random access response. Legacy randomaccess response message format may be employed for when multiple cellgroups are configured.

The wireless device may transmit uplink data on the first secondary cellin radio resources identified in the uplink grant at block 809. Therandom access response does not comprise an index identifying the firstsecondary cell. The wireless device applies the uplink grant to the cellthat was employed for preamble transmission. This may reduce signalingoverhead by eliminating inclusion of a cell index in the random accessresponse. Legacy random access response message format may be employedfor when multiple cell groups are configured.

According to some of the various aspects of embodiments, after randomaccess preamble transmission, the wireless device may monitor a downlinkcontrol channel on the primary cell for random access responsesidentified by an identifier (RA-RNTI). The monitoring may performedwithin a time frame. The time frame may start at a subframe thatcontains the end of transmission of the random access preamble plus ksubframes (k an integer greater than one, for example k=3). The timeframe may have a duration smaller than or equal to a random accessresponse window. The identifier of the random access response (RA-RNTI)may depend, at least in part, on: a subframe index (t_id) associatedwith a subframe in which the random access preamble is transmitted, anda frequency index (f_id) associated with a frequency offset in therandom access resources employed for the random access preambletransmission. For example, RA-RNTI may be calculated usingRA-RNTI=1+t_id+10*f_id. The random access response corresponds to therandom access preamble transmission employing an identifier of therandom access response and a preamble identifier identifying the randomaccess preamble.

The wireless device may receive an activation command to activate thefirst secondary cell in the wireless device prior to receiving thecontrol command. The control command may comprise an index identifyingthe first secondary cell only if the control command is not transmittedon the first secondary cell. The wireless device may transmit the randomaccess preamble in the random access resources of the first secondarycell.

The control command may be received on a scheduling cell of the firstsecondary cell. The control command may comprise a mask index and apreamble identifier identifying the random access preamble. The wirelessdevice may be assigned, by the configuration, a plurality of mediaaccess control dedicated parameters. The plurality of media accesscontrol dedicated parameters may comprise a plurality of time alignmenttimer values. Each time alignment timer value may be associated with aunique cell group in the wireless device.

FIG. 9 is an example flow diagram illustrating a base station randomaccess process as per an aspect of an embodiment. According to some ofthe various aspects of embodiments, a base station may comprise one ormore communication interfaces, one or more processors, and memorystoring instructions that, when executed, cause the base station toperform certain tasks. The base station may transmit at least onecontrol message to a wireless device at block 900. The at least onecontrol message may be configured to cause in the wireless deviceconfiguration of a plurality of cells and assignment of each of the atleast one secondary cell to a cell group in a plurality of cell groups.The plurality of cells may comprise a primary cell and at least onesecondary cell. The at least one control message may be configured tofurther cause in the wireless device configuration of a time alignmenttimer for each of the plurality of cell groups. The time alignment timermay start or restart in response to the wireless device receiving atiming advance command to adjust uplink transmission timing of acommanded cell group in the plurality of cell groups. The at least onecontrol message may comprise a plurality of common parameters for thefirst secondary cell. The plurality of common parameters may comprise: aplurality of random access resource parameters identifying the randomaccess resources, and a plurality of power control parameters.

The plurality of cell groups may comprise a primary cell group and atleast one secondary cell group. The primary cell group may comprise afirst subset of the plurality of cells. The first subset may comprisethe primary cell. A secondary cell group in the at least one secondarycell group may comprise a second subset of the at least one secondarycell. The base station may transmit a control command configured tocause transmission of a random access preamble on random accessresources of a first secondary cell in the at least one secondary cell.The base station may receive the random access preamble from thewireless device at block 902. The base station may transmit a randomaccess response corresponding to the random access preamble reception onthe primary cell of the primary cell group at block 905. The randomaccess response may comprise a timing advance command and an uplinkgrant. The base station may receive uplink data from the wireless deviceon the first secondary cell in radio resources identified in the uplinkgrant at block 909. The base station may intend the uplink grant for thefirst secondary cell without including the first secondary cell index inthe random access response. The timing advance command transmitted bythe base station may be configured to cause substantial alignment ofreception timing of uplink signals in frames and subframes of a firstsecondary cell group comprising the first secondary cell. The basestation may intend the timing advance command for the first secondarycell group comprising the first secondary cell without including thefirst secondary cell group index in the random access response. Therandom access response may not comprise an index identifying the firstsecondary cell group. The random access response may not comprise anindex identifying the first secondary cell.

According to some of the various aspects of embodiments, upon receivingUE's preamble, the eNB may transmit Msg2 603 RAR in the Msg2 603 window.The UE may receive a Msg2 603 RAR during the Msg2 603 window; if the UEreceives the RAR successfully, the UE may consider RA successful,otherwise the UE may retransmit a preamble (if preamble retransmissionis allowed). If preamble retransmission is not allowed or a maximumnumber of retransmissions is received, the UE may not retransmit thepreamble. The retransmission window size may be configured by radioresource control messages. The retransmission window size may beconfigured for a pCell. A RAR window size for a random access process onsecondary cells may employ the window size configured for the primarycell. This process may reduce flexibility in configuring differentrandom access window sizes for random access processes of a primary celland secondary cell(s). This may reduce signaling overhead. With thisconfiguration, a UE may not need to store and/or maintain multiplerandom access window size values, and the same value may apply to allrandom access processes. A RAR window size may be configured as a commonparameter. Common parameters for a pCell may have the same value for theprimary cell of different wireless devices.

Various RAR window sizes may be supported. RAR window sizes of (2, 3, 4,5, 6, 7, 8, or 10 ms) may be configured. A single RAR window size may besupported by the UE and eNB, and the same RAR may be used regardless ofwhich cell is employed for carrying a random access process. This mayreduce flexibility in configuring multiple RAR window times fordifferent cells in sTAG and pTAG. The RAR window may be configuredconsidering the maximum allowed number of retransmissions for the randomaccess message.

According to some of the various aspects of embodiments, random accesschannel common configuration parameters for a pCell may comprise thefollowing parameters: power ramping step, preamble initial receivedtarget power, maximum preamble transmission, random access responsewindow size, and/or the like. Random access channel common configurationparameters for an sCell may comprise the following parameters: powerramping step, preamble initial received target power, maximum preambletransmission, and/or the like. Other parameters may be included incommon configuration parameters. As shown in the example, secondarycells may not be configured with a random access response window size.The value of a random access response window size configured for thepCell may apply for random access processes for all cells with aconfigured random access resource. The associated functionality in therandom access process may be performed independently for each cell, butall random access functionalities may employ the same window value. Inan example embodiment, random access processes on an sCell may employthe random access response window size configured for the primary cell.

FIG. 10 is an example flow diagram illustrating a random access processin a wireless device as per an aspect of an embodiment. According tosome of the various aspects of embodiments, a wireless device may beconfigured to communicate employing a plurality of cells. The wirelessdevice may receive at least one control message from a base station atblock 1000. The at least one control message may cause in the wirelessdevice configuration of a primary cell and at least one secondary cellin the plurality of cells. The at least one control message may cause inthe wireless device assignment of each of the at least one secondarycell to a cell group in a plurality of cell groups. The plurality ofcell groups may comprise a primary cell group and a secondary cellgroup. The primary cell group may comprise a first subset of theplurality of cells. The first subset may comprise the primary cell. Thesecondary cell group may comprise a second subset of the at least onesecondary cell. The at least one control message may comprise a primaryrandom access response window parameter for the primary cell and/or apower ramping step value for each cell in a first plurality of cellshaving configured random access resources. The at least one controlmessage may not comprise a random access response window for secondarycells with configured random access resources.

According to some of the various aspects of embodiments, the wirelessdevice may transmit a random access preamble with an initialtransmission power on random access resources of a cell in the firstplurality of cells at block 1002. The random access preambletransmission may be in response to receiving a control command (PDCCHorder) from the base station. The wireless device may monitor a downlinkcontrol channel (PDCCH) on the primary cell for the corresponding randomaccess response at block 1005. The wireless device may monitor the PDCCHcommon search space for a PDCCH packet identified by a RA-RNTIcorresponding to the random access preamble transmission. PDCCH packetwith RA-RNTI comprises scheduling information of random accessresponse(s) transmitted in PDSCH. Random access response(s) with theRA-RATI are received and decoded by the wireless device. The wirelessdevice then looks for a corresponding random access response comprisingthe transmitted random access preamble. If the wireless device does notfind the corresponding random access response, the wireless devicecontinues monitoring the PDCCH common search space.

The monitoring for the corresponding random access response may beperformed within a time frame. The time frame may start at a subframethat contains the end of transmission of the random access preamble plusk subframes. k may be an integer greater than one (for example, k=3) andhave the same value regardless of which cell in the first plurality ofcells is employed for transmission of the random access preamble. Thetime frame may have duration smaller than or equal to the primary randomaccess response window regardless of which cell in the first pluralityof cells is employed for transmission of the random access preamble. Thewireless device may retransmit, with an increased transmission power,the random access preamble on the random access resources if nocorresponding random access response is received within the time frameat block 1007. The increased transmission power may depend, at least inpart, on the power ramping step value corresponding to the cell in thefirst plurality of cells.

According to some of the various aspects of embodiments, uplinktransmissions by the wireless device in the primary cell group mayemploy the primary cell as a primary timing reference cell. Uplinktransmissions by the wireless device in the primary cell group mayemploy a first synchronization signal transmitted on the primary cell asa primary timing reference. Uplink transmissions in the secondary cellgroup may employ an activated secondary cell in the secondary cell groupas a secondary timing reference cell. Uplink transmissions in thesecondary cell group may employ a second synchronization signal on anactivated secondary cell in the secondary cell group as a secondarytiming reference.

According to some of the various aspects of embodiments, thecorresponding random access response may comprise a timing advancecommand, an uplink grant, and a preamble identifier identifying therandom access preamble. The wireless device may apply the timing advancecommand to uplink transmission timing of a cell group comprising thecell. The wireless device may transmit uplink data on the cell in radioresources identified in the uplink grant. The random access response maynot comprise an index identifying a cell group comprising the cell. Therandom access response may not comprise may not comprise an indexidentifying the cell. An identifier of the random access response(RA-RNTI) may depend, at least in part, on a subframe index associatedwith a subframe in which the random access preamble is transmitted(t_id) and a frequency index associated with a frequency offset in therandom access resources employed for transmission of the random accesspreamble (f_id). According to some of the various aspects ofembodiments, the random access preamble may be transmitted only one timeif the corresponding random access response is received after the firsttransmission of the random access preamble.

In a random access process in a secondary cell group, the wirelessdevice may repeatedly transmit the random access preamble until thecorresponding random access response is received, or a firstpredetermined number of transmissions is reached. If the firstpredetermined number of transmissions is reached without receiving thecorresponding random access response and if the cell is in the secondarycell group, the wireless device may stop transmission of the randomaccess preamble, and may keep a connection with the base station active.Keeping the connection with the base station active implies that thedevice may remain in RRC connected state.

In a random access process in the primary cell group The wireless devicemay repeatedly transmit the random access preamble until thecorresponding random access response is received, or a secondpredetermined number of transmissions is reached. If the secondpredetermined number of transmissions is reached without receiving thecorresponding random access response and if the cell is in the primarycell group, the wireless device may indicate a random access problem toa radio resource control layer in the wireless device, and the radioresource control layer may determine a radio link failure.

According to some of the various aspects of embodiments, the at leastone control message may comprise a plurality of media access controldedicated parameters. The plurality of media access control dedicatedparameters may comprise a plurality of time alignment timer values. Eachtime alignment timer value may be associated with a unique cell group inthe wireless device. The at least one control message may further causein the wireless device configuration of a time alignment timer for eachof the plurality of cell groups. The time alignment timer may start orrestart in response to the wireless device receiving a timing advancecommand to adjust uplink transmission timing of a commanded cell groupin the plurality of cell groups. The at least one control message maycomprise a plurality of common parameters for the cell. The plurality ofcommon parameters may comprise a plurality of random access resourceparameters identifying the random access resources.

According to some of the various aspects of embodiments, an eNB inrelease 11 or above may support configurations including multiple TAGs.In example embodiments, different methods for updating TAGconfigurations may be presented. A UE may not be required to provideadditional assistant information for managing TAGs. An eNB may detectthe need for an SCell TAG change and determine the correct TAG for anSCell based on the UE uplink transmissions (for example PUSCH and/orSRS) or RACH preamble transmissions. In some scenarios, an eNB may needto initiate a random access procedure to detect the need for a TAGchange or determine the proper TAG for a given SCell. This scenario mayhappen, for example, when a new SCell is being configured or due to UEmobility to a repeater coverage area. In some other scenarios, an eNBmay realize the proper TAG for a given SCell based on normal uplinktransmissions (for example PUSCH and/or SRS). RRC signaling may be usedto associate an SCell with a TAG.

The sTAG change procedure may require special attention, because someimplementations may require a random access process to determine aproper TAG for an SCell. In some other scenarios, an eNB may desire tochange a TAG configuration for one or more TAGs. These processes are newto R.11 LTE, since prior releases did not support multiple TAGs in thenetwork. An efficient method should be introduced for TAGreconfiguration and timing reference SCell modifications. Disclosedmethods may reduce or eliminate unintended consequences and reducepossible unknown situations and reduce interference due to timingmisalignment.

There are many possible scenarios which might lead to a TAG change. AneNB may detect the need for an SCell TAG change and determine thecorrect TAG based on the normal UL transmission. In an exampleembodiment, an eNB may detect the need for an SCell TAG change byinitiating an RA process on the concerned SCell. An eNB may alsodetermine an SCell TAG change according to many other parameters, forexample, UE location, repeater related signaling, and/or the like. AnSCell may be re-grouped to an existing TAG with a valid TA value (TAGin-sync) or the SCell may be included in a newly configured TAG. In someother scenarios, when a new SCell is configured, RRC configurationmessages may configure a new TAG for the new SCell. In another example,when the UE moves out of the coverage area of a repeater, the SCell(s)belonging to sTAG may be moved to the pTAG.

According to some of the various aspects of embodiments, a scenario maybe considered wherein no new TAG is configured and the configuration ofTAGs is modified. For example, on detecting that an SCell is no longersuitable for the current TAG, based on the normal UL transmission(PUSCH, SRS) or preamble transmission, the eNB may initiate the TAGchange procedure. Then the eNB may change the concerned SCell TAG viaRRC signaling. An eNB may first release the SCell and then add theconcerned SCell to an existing TAG. This may be performed via one ormore RRC signaling messages. The SCell may be initially deactivated whenit is configured with an existing TAG.

According to some of the various aspects of embodiments, a scenario maybe considered wherein an eNB may not know the TA value for the concernedSCell and an eNB may not be able to determine if the concerned SCell maybe assigned to an existing TAG or a new TAG. This might be, for example,because the concerned SCell is a newly configured SCell or is anexisting SCell for which a TA may not be determined based on uplinktransmissions. When timing alignment of the concerned SCell does notmatch its existing sTAG, the concerned SCell may require TAGreconfiguration.

An eNB may configure a new sTAG for the concerned SCell, and thentrigger an RA on the concerned SCell to determine its timing alignmentvalue. The eNB may determine which TAG is the most suitable TAG for theconcerned SCell. The eNB may reconfigure the concerned SCell and movethe concerned SCell to a different TAG based on its TA value or keep theconcerned SCell and newly added sTAG configuration. The eNB may need todetect the need for a TAG change and determine the correct TAG based onthe TA value of the concerned SCell by triggering an RA procedure on theSCell. The eNB may not transmit a RAR if the eNB desires to change theTAG of the SCell. This process of TAG reconfiguration may requiretransmitting at least one RRC reconfiguration message.

If an eNB suspects that the concerned SCell is no longer suitable forthe current TAG based on the received signal timing of UE ULtransmissions (for example PUSCH, and/or SRS transmission), the eNB mayinitiate the TAG change procedure. The eNB may trigger an RA procedureon the concerned SCell to obtain the TA value of this concerned SCelland may change its TAG (if needed) via the RRC signalling. The eNB mayrelease the concerned SCell and add it to a suitable or new TAG. In thiscase, UL data and SRS transmission may be initially stopped on theconcerned SCell where a TA group is set to the new TAG because the SCellis deactivated when the SCell is added to the new TAG. In an examplescenario, a TA timer of the new TA group may not be running. An RAprocedure may be implemented to acquire a new TA value and to start anew TA timer for the usage of concerned UL SCell in the new TA group. Ifthe concerned SCell was a reference SCell in a current sTAG and is movedout of a current sTAG, then the UE may select another active SCell inthe current sTAG as the timing reference in the current sTAG.

According to some of the various aspects of embodiments, a cell groupindex may be configured as a dedicated radio resource configurationparameter for an sCell. The dedicated radio resource configurationparameters for an sCell may be configured as a part of anSCell-To-Add-Modify parameter. If the dedicated radio resourceconfiguration parameters of an sCell comprise a cell group index for afirst secondary cell, the secondary cell may be assigned to a secondarycell group identified by the cell group index. Otherwise, the firstsecondary cell may be assigned to a primary cell group. According to anexample embodiment, the dedicated radio resource configurationparameters of an sCell may not modify the cell group index of an alreadyconfigured cell. The cell group index may be configured only when thesCell is added (configured). If an eNB needs to change the cell groupindex of an already configured sCell, the eNB may need to release(remove) the sCell and configure (add) the sCell with a new updated cellgroup index (pTAG index or sTAG index). The added sCell may have thesame physical cell identifier and downlink frequency. The added sCellmay be assigned the same sCell index. In an example embodiment, theadded sCell may be assigned a different sCell index. This process may beapplicable, when there is no handover. A different process may beapplicable when the RRC message includes a handover configuration.

FIG. 11 is an example flow diagram illustrating a change in timingadvance group configuration as per an aspect of an embodiment. Accordingto some of the various aspects of embodiments, a base station may beconfigured to communicate employing a plurality of cells. The basestation may transmit at least one first radio resource control messageto a wireless device at block 1100. The at least one first radioresource control message may be configured to cause in the wirelessdevice configuration of a primary cell and at least one secondary cellin the plurality of cells. The at least one first radio resource controlmessage may be configured to cause assignment of each of the at leastone secondary cell to one cell group in at least one cell group. A cellgroup in the at least one cell group may comprise a subset of theplurality of cells. Uplink transmissions of the wireless device in thecell group may employ a reference timing cell. Uplink transmissions ofthe wireless device in the cell group may employ a synchronizationsignal on an activated cell in the cell group as a timing reference.

The base station may detect a change in timing of signals received fromthe wireless device in a first secondary cell in a first cell group atblock 1102. The timing of signals received from the wireless device maychange due to wireless device mobility or due to changes in thepropagation environment. For example, the wireless device may move inthe coverage area of a repeater or may move out of the coverage area ofa repeater. The base station may transmit one or more timing advancecommand to align uplink timing of the wireless device.

The at least one cell group may comprise a primary cell group and asecondary cell group. The primary cell group may comprise a first subsetof the plurality of cells. The first subset may comprise the primarycell. Uplink transmissions by the wireless device in the primary cellgroup may employ a first synchronization signal transmitted on theprimary cell as a primary timing reference. The secondary cell group maycomprise a second subset of the at least one secondary cell. Uplinktransmissions in the secondary cell group may employ a secondsynchronization signal on an activated secondary cell in the secondarycell group as a secondary timing reference.

The at least one first radio resource control message may comprise aplurality of media access control dedicated parameters. The plurality ofmedia access control dedicated parameters may comprise a deactivationtimer value.

The at least one third radio resource control message may comprise aplurality of dedicated parameters for the first secondary cell. Theplurality of dedicated parameters may be specific to the wirelessdevice. If the plurality of dedicated parameters comprise a cell groupindex for the first secondary cell, the first secondary cell may beassigned to a secondary cell group identified by the cell group index.Otherwise, the first secondary cell is assigned to a primary cell group.Basically, RRC messages causing configuration of secondary cell(s)assigned to a primary cell group may not include a cell index and thosesecondary cells without a cell index may be implicitly assigned to theprimary timing advance group. The RRC message configuration parametersthat causes configuration of secondary cell(s) assigned to the primarycell group may not explicitly comprise a cell group index.

According to some of the various aspects of embodiments, the change inthe timing of signals received in the first secondary cell may bedetected by a comparison of the received signal timings with a referenceframe timing in the base station. The change in the timing of signalsreceived in the first secondary cell may be detected by a comparison ofthe received signal timing with timing of another cell in the first cellgroup. The change in the timing of signals received in the firstsecondary cell may be detected by a comparison with timing of signalsreceived in the primary cell. The base station may detect that theuplink signal timing change employing other similar or differentimplementation specific mechanisms.

The base station may selectively, and depending on the characteristicsof the change in timing, transmit one or more timing advance commands toalign uplink timing of the cells. In some scenarios, the timing may notbe align-able employing one or more timing advance commands. Forexample, the wireless device may transmit on a primary cell in a firstband and on a secondary cell on a second band. The wireless device maymove in the coverage area of a single band repeater for the second band.The single band (second band) repeater may cause additional delay inuplink signals of a secondary cell received by a base station (but maynot affect the signals of a primary cell). The delay caused by therepeater may not be align-able by the base station if the primary celland the secondary cells are in the same timing advance group. Otherscenarios may also be possible depending on the mobility of the wirelessdevice and network settings and configuration.

The base station may determine that the change in timing may be alignedemploying one or more timing advance commands. In another scenario, thebase station may determine that the first secondary cell needs to beassigned to a different cell group than the first cell group as shown atblock 1105. In an example embodiment, the base station may determinethat the first secondary cell needs to be assigned to a different cellgroup if the timing of signals is aligned with a timing of signalsreceived in the primary cell. In another example embodiment, the basestation may determine that the first secondary cell needs to be assignedto the different cell group if the timing of signals with the changecannot be aligned employing at least one timing advance command. Otherexample scenarios on how the base station determines that the cell groupneeds to changed or does not need to be changed may be provided asimplementation options.

The first secondary cell may have a downlink carrier frequency and aphysical cell identifier. The downlink carrier frequency and physicalidentifier of the first secondary cell does not change due to timingadvance group re-configuration. The downlink carrier frequency andphysical identifier are physical characteristics of the cell and may notchange when the cell is configured. Other example physical parametersthat may not be reconfigured may include bandwidth, common referencesignals, and/or the like.

In an example implementation the first cell group may be a primary cellgroup. The second cell group may be a secondary cell group. In anotherexample embodiment, the first cell group may be a secondary cell group,and the second cell group may be a primary cell group. The at least onefirst radio resource control message may be configured to causeassignment of a first cell index to the first secondary cell.

If the base station determines that the cell group configuration needsto be changed, the base station may start a timing advance groupconfiguration change process by transmitting one or more RRC messages tothe wireless device. Such a signaling process is not applicable torelease 10 or earlier releases of LTE technology. Signaling mechanismsmay be developed to address this TAG configuration change, when a basestation detects/decides that TAG configuration should be changed.Different embodiments may be implemented to change timing advance groupconfigurations. In this disclosure, different embodiments are presentedto change a current timing advance configuration of a wireless device.

According to some of the various aspects of embodiments, the basestation may transmit at least one second radio resource control (RRC)message configured to cause in the wireless device release of the firstsecondary cell at block 1107. The cell that requires a cell group changemay be released employing an SCellToReleaseList-r10 information elementemploying the SCell index. If TAG configuration of more than one SCellneeds to be changed, SCellToReleaseList-r10 may include a list of morethan one SCell index.

The base station may transmit at least one third radio resource controlmessage configured to cause in the wireless device configuration of thefirst secondary cell at block 1107. The configuration may assign thefirst secondary cell to a second cell group different from the firstcell group. The SCell may be deactivated in the wireless device when itis configured. The at least one third radio resource control message maybe configured to cause assignment of the same the first cell index tothe first secondary cell. Physical parameters such as physical cell IDand downlink frequency of the first secondary cell may not change whenit is released and configured again. The base station may transmit anactivation command to activate the first secondary cell in the wirelessdevice.

In another embodiment, the cell index of the first secondary cell may bechanged after it is released and then configured employing at least onethird radio resource control message. There are a limited number of cellindex available for the base station and base station may assign SCellindexes to secondary cells when a secondary cell is configured.

According to some of the various aspects of embodiments, the basestation may transmit at least one second control message configured tocause in the wireless device: release of the first secondary cell havinga first cell index and configuration of the first secondary cell with asecond cell index different from the first cell index at block 1107. Thesame radio resource message may release the first secondary cell andthen configure the first secondary cell. The cell that requires a cellgroup change may be released employing an SCellToReleaseList-r10information element employing the first SCell index. If TAGconfiguration of more than one SCell needs to be changed,SCellToReleaseList-r10 may include a list of more than one SCell index.The same radio resource control message may configure the firstsecondary cell in a different cell group. The first secondary cell maybe configured employing the SCellToAddMod-r10 in the at least one secondcontrol message. The same first secondary cell that is released in aradio resource control message may be added (configured) employing thesame radio resource control message.

SCellToAddMod-r10 may cause configuration of the first secondary cell.The configuration of the first secondary cell may cause assignment ofthe first secondary cell to a second cell group different from the firstcell group. The same RRC message releases and adds the first secondarycell. The first secondary cell may assign a different SCell index beforeit is released and after it is added. The RRC message may useSCellToReleaseList-r10 for the first index of the first secondary cell.And then the RRC message may use SCellToAddMod-r10 and add the samefirst secondary cell with a different SCell index than the first index.They physical Cell ID and downlink frequency of the first secondary cellremains the same. The first secondary cell may be deactivated after itis added (configured). The base station may transmit an activationcommand to activate the first secondary cell in the wireless device.

According to some of the various aspects of embodiments, the basestation may transmit at least one second control message configured tocause in the wireless device: release of the first secondary cell havinga first cell index and configuration of the first secondary cell with asame first cell index at block 1107. The same radio resource message mayrelease the first secondary cell and then configure the first secondarycell with the same cell index. The cell that requires a cell groupchange may be released employing an SCellToReleaseList-r10 informationelement employing the first SCell index. If TAG configuration of morethan one SCell needs to be changed, SCellToReleaseList-r10 may include alist of more than one SCell index. The same radio resource controlmessage may configure the first secondary cell in a different cellgroup. The first secondary cell may be configured employing theSCellToAddMod-r10 in the at least one second control message. The samefirst secondary cell that is released in a radio resource controlmessage may be added (configured) employing the same radio resourcecontrol message.

SCellToAddMod-r10 may cause configuration of the first secondary cell.The configuration of the first secondary cell may cause assignment ofthe first secondary cell to a second cell group different from the firstcell group.

The same RRC message releases and adds the first secondary cell. Thefirst secondary cell may be assigned the same SCell index before it isreleased and after it is added. The RRC message may useSCellToReleaseList-r10 for the first index of the first secondary cell.And then the RRC message may use SCellToAddMod-r10 and add the samefirst secondary cell with the same SCell index as the first index. Inorder to maintain the same SCell index, the information elements in anRRC message content may be ordered in a way that SCellToReleaseList-r10is processed before SCellToAddMod-r10. The wireless device may processSCellToReleaseList-r10 with the first SCell index, and then add(configure) the first secondary cell by processing SCellToAddMod-r10that adds the first secondary cell with the same SCell index. Thisprocess for SCell configuration enhances the overall efficiency andreduces overhead, because not only it requires one RRC message forrelease and addition of the same first secondary cell, it also employsthe same SCell index for the first secondary cell before SCell releaseand after SCell addition. The proper order of information elements inRRC message in this embodiment enables release and addition of the sameSCell without changing the SCell index. The order may be definedaccording to a pre-defined processing order rule in the base station andwireless device. The order may be based on sequential order, or may beaccording to any order rule on how to process information elements in anRRC message as they are arrange in the RRC message and as they areprocessed by the wireless device. SCellToReleaseList-r10 may beprocessed before SCellToAddMod-r10, otherwise the processing of the RRCmessage may result in an error scenario. If SCellToAddMod-r10 adds anSCell with the same cell index and then SCellToReleaseList-r10 releasethe SCell, at least one or both of the processes may result in error anscenario.

They physical Cell ID and downlink frequency of the first secondary cellmay also remain the same. The first secondary cell may be deactivatedafter it is added (configured). The base station may transmit anactivation command to activate the first secondary cell in the wirelessdevice. A cell index may remain the same before the at least one secondcontrol message is transmitted and after the at least one second controlmessage is processed.

According to some of the various aspects of embodiments, multiple randomaccess procedures may not be processed in parallel in the UE. In otherwords, only one RA process may run at a time. An eNB may not startparallel RA processes and the UE may not have the capability of paralleltransmission of preambles on multiple cells. A UE may start a randomaccess process on a second cell when a random access process on a firstcell has terminated. The termination may be due to, for example: asuccessful RA process, a failure in an RA process, or an aborted ongoingrandom access process. In some situations, error cases may occur, forexample, an eNB may detect that the random access process has beenterminated, while a UE may still be in an on-going RA process. This maybe for various reasons including signal loss or misdetection in a radiointerface, other reasons such as processing errors in the UE or eNB,and/or the like. For many unpredicted causes, an eNB may improperlyassume that a random access process is terminated while a UE is stillcontinuing a random access process. Examples of unpredictable reasonsmay include: the UE still waiting for a RAR or the UE planning to send apreamble in the uplink. When the UE is in a poor coverage area, theprobability of such an error scenario may increase.

An eNB may transmit a PDCCH order to a UE for preamble transmission on aCell while a UE is still in a random access process in the same or adifferent cell. In an example embodiment, such a condition may beconsidered an error scenario. If the UE receives a PDCCH order whilethere is an ongoing RA process in the UE, the UE may abort the ongoingRA procedure. The UE may stop the existing RA process and clear itsparameters. The UE may process the received PDCCH order. The UE maytransmit a random access preamble based on the new PDCCH order and mayrestart associated timers and may configure random access parametersaccording to the new PDCCH order. In this example implementation, the UEmay have the same state with the eNB on the SCell where the RA procedureis running. By following a BS order, the UE may reset the error scenarioand UE state and parameters may become compatible with the random accessstate and parameters in the eNB. For example, the preamble usage and RAresource usage parameters may be the same in the UE and eNB after thenew PDCCH order is processed.

An RA process may be considered running, for example, if thecorresponding timers are still running. Examples of corresponding timesinclude a RAR window timer, and/or the like. A RA process may beconsidered running if the maximum number of allowed preambletransmissions has not been achieved yet. A random access response may beconsidered terminated, for example, when a valid RAR is received from aneNB or when a UE transmits a packet in response to RAR.

In another example embodiment, an eNB may intend for a PDCCH order to bereceived while an RA is running. An eNB may purposefully transmit aPDCCH order while a UE is in an ongoing random access process. This maybe used as a tool to terminate an existing random access process andstart a new one. An eNB may transmit a PDCCH order when there is anongoing RA process in the UE. This may be for example: because an eNBhas decided that the SCell is not the proper SCell for the timingreference, or because the eNB detected a new SCell in the sTAG which maybe a better candidate to be the reference timing SCell. In the exampleembodiments, the UE may not ignore a received PDCCH order when it is inan ongoing RA procedure. When a UE receives a PDDCH order for preambletransmission, the UE may abort the ongoing RA procedure and then start anew RA procedure based on the newly received PDCCH order.

In another example embodiment, RA processes may be assigned differentpriorities. For example, an RA process on a pCell may be assigned ahigher priority than an RA process on an sCell. When a PDCCH order isreceived for a preamble transmission when an RA process with the same orlower priority is running, the running random access process may beaborted and a new RA process according to the PDCCH order may bestarted. But, if a PDCCH order has been received for starting an RA onan SCell while the UE is running an RA process on a pCell, then the UEmay ignore the PDCCH order and continue its ongoing RA on the pCell. AnRA on a pCell may be more important than an RA on an sCell. A successfulRA process on a pCell may prevent a radio link failure in some examplescenarios, for example, when a UE has determined that it has lost (or isclose to losing) the pTAG timing and the UE (or eNB) has started a RA togain uplink pTAG timing.

In another example embodiment, a similar process may be applied in theeNB when the eNB receives a preamble on a pCell while the eNB is in anongoing RA process with an sTAG. In this scenario, the eNB may abort theongoing RA process on the sTAG and may start the RA process on the pTAG.The eNB may assume that the UE has aborted the RA process in the sTAGand that the UE has started an RA process on the pTAG.

FIG. 12 is an example flow diagram illustrating random access process(s)as per an aspect of an embodiment of the present invention. According tosome of the various aspects of embodiments, a wireless device may beconfigured to communicate employing a plurality of cells. The wirelessdevice may receive at least one control message from a base station atblock 1200. The at least one control message may cause in the wirelessdevice configuration of a primary cell and at least one secondary cellin the plurality of cells. The at least one control message may cause inthe wireless device assignment of each of the at least one secondarycell to a cell group in a plurality of cell groups. The plurality ofcell groups may comprise a primary cell group and a secondary cellgroup. The primary cell group may comprise a first subset of theplurality of cells. The first subset may comprise the primary cell. Thesecondary cell group may comprise a second subset of the at least onesecondary cell. Uplink transmissions by the wireless device in theprimary cell group may employ a first synchronization signal transmittedon the primary cell as a primary timing reference. Uplink transmissionsin the secondary cell group may employ a second synchronization signalon an activated secondary cell of the secondary cell group as asecondary timing reference.

The wireless device may initiate a first random access process on afirst uplink carrier of a first cell in the plurality of cells inresponse to receiving a first control command at block 1202. Thewireless device may receive a second control command for transmission ofa second random access preamble on a second uplink carrier of a secondcell in the plurality of cells while the first random access process ison-going at block 1205. In an example embodiment, the second cell may bedifferent from the first cell. The wireless device may determineemploying a pre-defined rule: to continue with the first random accessprocess and ignore the second control command, or to abort the firstrandom access process and to transmit the second random access preambleat block 1207.

According to some of the various aspects of embodiments, pre-definedrules may be defined in the wireless device. In one exampleimplementation, the pre-defined rule may determine to continue with thefirst random access process if: the first cell is the primary cell, andthe second cell is a secondary cell in the secondary cell group. Inanother example embodiment, the pre-defined rule may determine tocontinue with the first random access process if: the first cell is asecondary cell in the secondary cell group, and the second cell is theprimary cell. In another example embodiment, the pre-defined rule maydetermine to continue with the first random access process and ignorethe second control command.

According to some of the various aspects of embodiments, the at leastone control message may be configured to further cause in the wirelessdevice configuration of a time alignment timer for each of the pluralityof cell groups. The time alignment timer may start or restart inresponse to the wireless device receiving a timing advance command toadjust uplink transmission timing of a commanded cell group in theplurality of cell groups. The first control command may comprise: a maskindex and a preamble identifier of a random access preamble. The firstcontrol command may further comprise an index identifying the first cellonly if the control command is not transmitted on the first cell. Thefirst control command may further comprise an index identifying thefirst cell only if the control command is not transmitted on the firstcell. The at least one control message may further cause in the wirelessdevice configuration of random access resources for the first cell andthe second cell. The at least one control message may comprise aplurality of common parameters for the first cell and the second cell.The plurality of common parameters may comprise a first plurality ofrandom access resource parameters and a second plurality of randomaccess resource parameters. The first plurality of random accessresource parameters may identify first random access resources for thefirst cell. The second plurality of random access resource parametersmay identify second random access resources for the second cell.

According to some of the various aspects of embodiments, a wirelessdevice may receive at least one control message from a base station atblock 1200. The at least one control message may cause in the wirelessdevice configuration of a primary cell and at least one secondary cellin the plurality of cells. The at least one control message may cause inthe wireless device assignment of each of the at least one secondarycell to a cell group in a plurality of cell groups. The plurality ofcell groups may comprise a primary cell group and a secondary cellgroup. The wireless device may initiate a first random access process ona first uplink carrier of a first cell in the plurality of cells inresponse to receiving a first control command at block 1202. Thewireless device may receive a second control command for transmission ofa second random access preamble on a second uplink carrier of a secondcell in the plurality of cells while the first random access process ison-going at block 1205. The wireless device may determine employing apre-defined rule: to continue with the first random access process andignore the second control command, or to abort the first random accessprocess and to transmit the second random access preamble at block 1207.

According to some of the various aspects of embodiments, pre-definedrules may be defined in the wireless device. In one exampleimplementation, the pre-defined rule may determine to abort the firstrandom access process if: the first cell is the primary cell, and thesecond cell is a secondary cell in the secondary cell group. In anotherexample implementation, the pre-defined rule determines to abort thefirst random access process if: the first cell is a secondary cell inthe secondary cell group; and the second cell is the primary cell. In anexample embodiment, the pre-defined rule may determine to abort thefirst random access process and to transmit the second random accesspreamble. In an example embodiment, the pre-defined rule determines tocontinue with the first random access process if the first random accesspreamble is transmitted before reception of the second control command;and to abort the first random access process if the second controlcommand is received before transmission of the first random accesspreamble.

According to some of the various aspects of embodiments, the second cellmay be the same as the first cell. The wireless device may receive asecond control command for transmission of a second random accesspreamble on an uplink carrier of a cell in the plurality of cells (atblock 1205) while the first random access process is on-going on thesame cell.

The wireless device determines to continue with the first random accessprocess if: the first cell is the primary cell; and the second cell isthe primary cell. For example, the wireless device may determine toabort the first random access process if: the first cell is the primarycell; and the second cell is the primary cell. In another example, thewireless device may determine to continue with the first random accessprocess if: the first cell is a secondary cell in the secondary cellgroup; and the second cell is also the secondary cell. In anotherexample, the wireless device determines to abort the first random accessprocess if: the first cell is a secondary cell in the secondary cellgroup; and the second cell is also the secondary cell.

Embodiments may determine UE behavior when a downlink timing referenceSCell and/or pathloss reference SCell of an sCell or sTAG are notproperly detected/decoded by a UE. For the case of a pCell, such ascenario may result in a radio link failure. Such a scenario for ansCell or sTAG may not result in a UE initiating a radio link failureprocedure. A UE may lose its timing because it is no longer obtainingits timing from a timing reference SCell. A UE may lose its timingbecause its pathloss reference is no longer obtaining a pathlossreference downlink carrier. This may be for various reasons, such as: apoor signal level, poor coverage quality due to high interferencelevels, deactivation of a reference SCell, a downlink timing jump on areference SCell or another SCell, a combination of these reasons, and/orthe like. In another example, a UE may move to the coverage area of arepeater, and some of the carriers (passing through the repeater) mayexperience a sudden delay in the downlink signal. A UE may not be ableto use an SCell as the path loss reference when the signal quality ofthe SCell is poor. When a UE does not have a proper timing reference foran uplink transmission, its uplink transmission may cause unwantedinterference. When a UE cannot detect the proper pathloss, the UE maynot be able to properly calculate its transmission power, and the UE maytransmit signals with extra power creating unwanted interference in thenetwork.

According to some of the various aspects of embodiments, a UE maysuspend uplink transmissions in affected SCells when the UE detects thatit does not have a proper uplink timing reference or when it is not ableto properly calculate the pathloss. An eNB may not be initially aware ofsuch a situation, and may schedule a UE for uplink transmission on thatsTAG or SCell. But, the UE may not execute eNB PDCCH commands and maysuspend uplink transmissions. In an example embodiment, a UE maytransmit a Channel Quality Indicator (CQI) of zero for cells that do nothave a valid timing reference or a valid pathloss reference. If a timingreference of a reference secondary cell is lost by a UE, the UE mayautonomously select another activated SCell in the secondary cell groupas the timing reference (if there is another activated SCell in thesecondary cell).

In an example embodiment, an sTAG may have one timing reference SCell ata given time for uplink PUSCH and SRS transmission. All SCells in ansTAG may use the same SCell timing reference. When a timing referencecannot be properly detected and there are no other active SCell in thesecondary cell group, the uplink transmission in uplink SCells in thesTAG may be suspended. In another example embodiment, a UE may suspenduplink transmissions after a time alignment timer associated with thesTAG expires. In an sTAG, a pathloss reference may be configuredexplicitly or implicitly on a per sCell basis. For example, the SIB2(system information block 2) downlink carrier associated with an uplinkcarrier may be used as the pathloss reference. Therefore, an SCell mayhave its own pathloss reference. When a UE cannot properly detect apathloss reference of an SCell, the UE may suspend uplink transmissionon that SCell. The UE may continue uplink transmission on other SCellsbelonging to the same sTAG if a pathloss reference for other SCells isproperly detected. This process may reduce unwanted interference in thenetwork. A pathloss reference may be configured on a per cell basis. Atiming reference may be configured on a per sTAG basis. In an exampleembodiment, a UE may transmit CQI zero for active cells without a validtiming reference or pathloss reference.

In an example scenario, an eNB may detect an insufficient signal qualityby: receiving CSI feedback, an SRS signal from a UE, by observing ahigher than desired bit error rate in the uplink signals of an SCell ofthe UE, and/or the like. An eNB may then take actions such as:de-configuring or deactivating the SCell, not scheduling any uplinktransmission on that SCell for the UE, and/or the like. But if eNB doesnot take such an action, and if the UE does not detect its timingreference or pathloss reference, the UE may stop uplink transmissionsautonomously.

A eNB may detect that an unexpected UL timing loss and/or pathlossreference loss has occurred, for example, when the eNB assigns UL grantsto the UE but does not receive uplink packets from the UE. In anexample, an eNB may receive a CQI of zero for a given SCell. This maylead to unwanted wasted uplink resources until the eNB detects that theUE has lost its uplink timing. In an example embodiment, a UE may informthe eNB that it has lost timing or a pathloss reference for a givenSCell or sTAG. A UE may indicate to the eNB of the occurrence of theuplink timing loss and/or pathloss reference loss, for example, bysending an RRC or MAC level indication to the eNB. The eNB may take anaction such as not scheduling uplink packets in the sTAG or SCell,stopping SRS in that sTAG or SCell, starting an RA process on that sTAG,and/or the like. In another example embodiment, a UE may not inform thenetwork about the autonomously stopping uplink transmission. An eNB maydetect that the UE stopped uplink transmission, for example, by notreceiving any signal in the uplink of a given SCell. The UE may notexplicitly inform the eNB by sending a message to a UE informing the eNBabout the autonomous suspension. When a UE loses its timing reference inan sTAG, the UE may not initiate a random access process. The eNB maydetect that regular UL activities of the UE (e.g. SRS) are stopped andmay send a PDCCH order to establish a timing reference and uplink timingof the sTAG.

In an example embodiment, when a UE is unable to detect the downlinkreference timing for an sTAG or when there is a sudden timing jump inthe downlink timing of an SCell, the UE may inform the eNB that a changein timing has occurred or may inform the eNB that the timing is invalidor the UE has lost timing of an SCell or an sTAG. In another example, aUE may inform the eNB that the timing of an sTAG is invalid. In anotherexample, when the pathloss reference for an SCell is invalid, the UE mayinform the eNB that the pathloss reference is invalid.

According to some of the various aspects of embodiments, a wirelessdevice may be configured to communicate employing a plurality of cells.The wireless device may receive at least one control message from a basestation. The at least one control message may cause in the wirelessdevice configuration of a primary cell and at least one secondary cellin the plurality of cells. The at least one control message may cause inthe wireless device assignment of each of the at least one secondarycell to a cell group (implicitly or explicitly) in a plurality of cellgroups. The plurality of cell groups may comprise a primary cell groupand a secondary cell group. The primary cell group may comprise a firstsubset of the plurality of cells. The first subset may comprise theprimary cell. The secondary cell group may comprise a second subset ofthe at least one secondary cell. Uplink transmissions by the wirelessdevice in the primary cell group may employ a first synchronizationsignal transmitted on the primary cell as a primary timing reference.Uplink transmissions in the secondary cell group may employ a secondsynchronization signal on an activated secondary cell of the secondarycell group as a secondary timing reference.

The at least one control message may comprise a pathloss reference foreach secondary cell in the at least one secondary cell. The pathlossreference may be only configurable as a downlink of the secondary cellif the secondary cell is in the secondary cell group. The pathlossreference may be configurable as a downlink of the secondary cell or asa downlink of the primary cell if the secondary cell is in the primarycell group. The wireless device may transmit uplink signals to the basestation in a first secondary cell in the secondary cell group.Transmission power of the uplink signals may be determined, at least inpart, employing a received power of the pathloss reference assigned tothe first secondary cell. Timing of the uplink signals in the secondarycell group may employ a second synchronization signal on an activatedsecondary cell in the secondary cell group as a secondary timingreference. In an example implementation, the activated secondary cellmay be a first secondary cell. The activated secondary cell is differentfrom the first secondary cell.

According to some of the various aspects of embodiments, the wirelessdevice may stop, by the wireless device, transmission of uplinktransport blocks in the secondary cell group if the following conditionsare satisfied: the wireless device is unable to acquire timing of thesecond synchronization signal; and the secondary cell group does notcomprise any other active cells. This may be done regardless of if timealignment timer is running or not running. In an embodiment, thewireless device may stop transmission of uplink transport blocks in thesecondary cell group if the following conditions are satisfied: thewireless device is unable to acquire timing of the secondsynchronization signal; the secondary cell group does not comprise anyother active cells; and a time alignment timer corresponding to thesecondary cell group being expired. The wireless device may allow uplinktransmission of at least one random access preamble in the secondarycell group if the conditions are satisfied. The wireless device maycontinue transmission of channel state information for the firstsecondary cell on an uplink carrier not belonging to the secondary cellgroup if the conditions are satisfied. The wireless device may continuetransmission of HARQ feedback for transport blocks received on adownlink of the first secondary cell if the conditions are satisfied.

According to some of the various aspects of embodiments, the wirelessdevice may initiate a radio link failure if the wireless device isunable to acquire timing of the first synchronization signal regardlessof whether the wireless device acquires timing of the secondsynchronization signal. The wireless device may keep the connection withthe base station active if the wireless device is able to acquire timingof the first synchronization signal regardless of whether the wirelessdevice acquires timing of the second synchronization signal.

The wireless device may stop transmission of uplink transport blocks onthe first secondary cell if the wireless device is unable to measure areceived power of the pathloss reference for a period of time. Thetransmission power of the uplink signals may be determined, at least inpart, employing measurements of a received power of the pathlossreference assigned to the first secondary cell. The transmission powerof the uplink signals may be determined, at least in part, furtheremploying at least one power control parameter received in the at leastone control message. The transmission power of the uplink signals may bedetermined, at least in part, further employing at least one powercontrol command transmitted by the base station.

The wireless device may receive at least one control packet comprisingone or more power control commands. Transmission power of a plurality ofpackets transmitted by the wireless device may be calculated employing,at least in part: the received power of the pathloss reference assignedto the first secondary cell; and the one or more power control commands.

In an example embodiment, the wireless device may selecting,autonomously and without informing the base station, a new activatedsecondary cell in the secondary cell group as the secondary timingreference if the following conditions are satisfied: the wireless deviceis unable to acquire timing of the second synchronization signal; and atleast one secondary cell, different from the active secondary cell, inthe secondary cell group is active in the wireless device. The wirelessdevice may continue transmission of uplink signals in the secondary cellgroup.

According to some of the various aspects of embodiments, when a TATassociated with the pTAG expires, all TATs may be considered as expiredand the UE may: flush all HARQ buffers of all serving cells, clear anyconfigured downlink assignment/uplink grants, and/or the RRC may releasePUCCH/SRS for all configured serving cells. If the TAT associated withthe PCell expires, the TAT of all sTAGs may be stopped and/ordeconfigured.

UE behavior may be further defined when a TAT associated with the pTAGexpires, or when TAT has already expired, and/or when the pTAG isout-of-sync. For example, a PHY/MAC process may need to be specifiedwhen the UE: receives a PDCCH order for starting an RA process on ansTAG, is running an ongoing RA process on an sTAG, or receives a PDCCHorder on SCell PDCCH resources. A UE may avoid initiating and/orperforming processes that requires battery power consumption in thesesituations. A PHY/MAC process may increase battery power consumption.This may be especially important when the UE is in a poor coverageenvironment.

If the PCell TAT expires during an on-going sTAG RA procedure. The UEmay abort the on-going SCell RA procedure. The RA process may take arelatively long time, for example, when the UE is in poor coverageenvironment. For example, a UE may transmit the preamble multiple timeswhile ramping up power in re-transmissions. Every time a preamble istransmitted, a UE may wait until a RAR window expires, and mayretransmit a RA preamble until a maximum number of transmissions havebeen reached. In another example embodiment, an eNB may need to transmitRAR commands multiple times until a MAC RAR is successfully received.The UE may abort the random access procedure on an SCell if the TAT forthe PCell expires (and/or the pTAG becomes out-of-sync) during theprocedure. This may prevent or reduce the possibility of being in astate where an sTAG TAT is running while the pTAG TAT is not running. AnRA process may take a relatively long time, for example, 5, 10, 20, or50 msec when a subframe duration is approximately 1 msec. A UE may notstart or re-start the TAT of an SCell when the TAT of the pTAG is notrunning. If the pTAG TAT expires during an on-going sTAG RA procedure,the UE may stop the RA process on the sTAG. In an example embodiment, aUE may autonomously start an RA process on the pCell when the pTAG TATis expired to obtain uplink synchronization for the pTAG.

In another example embodiment, a UE may receive a PDCCH order toinitiate an RA process on an sTAG while its pTAG TAT is not runningand/or when the pTAG is out-of-sync. In this situation, the UE mayignore the received PDCCH order and may not start preamble transmissionon the sTAG. In another example embodiment, a UE may receive a TAcommand for an sTAG, when its pTAG TAT is not running. The UE may notstart or re-start the TAT of the SCell when the TAT of the pTAG is notrunning.

In another example embodiment, the UE may stop monitoring the PDCCH forall SCells when: the TAT associated with the pTAG expires, the TAT hasalready expired, and/or the pTAG is out-of-sync. This includes scenarioswhen cross-carrier scheduling is enabled or not enabled. This processmay reduce battery power consumption when the TAT for a pTAG is notrunning. In another example embodiment, when the pTAG is out-of-sync,even if the UE monitors the PDCCH for activated SCells, a UE may nottake any action when a PDCCH on an SCell or for an SCell (in case ofcross carrier scheduling) is received. No downlink transmissions oruplink transmissions on SCells may be allowed when a TAT for the pTAGexpires and/or the pTAG is out-of-sync. There may be no need to monitorPDCCH for an SCell when a TAT for the pTAG is not running.

FIG. 13 is an example flow diagram illustrating random access process(s)as per an aspect of an embodiment of the present invention. According tosome of the various aspects of embodiments, a wireless device may beconfigured to communicate employing a plurality of cells. The wirelessdevice may receive at least one control message from a base station atblock 1300. The at least one control message may cause in the wirelessdevice configuration of a primary cell and at least one secondary cellin the plurality of cells. The at least one control message may cause inthe wireless device assignment of each of the at least one secondarycell to a cell group (implicitly or explicitly) in a plurality of cellgroups. The plurality of cell groups may comprise a primary cell groupand a secondary cell group. The primary cell group may comprise a firstsubset of the plurality of cells. The first subset may comprise theprimary cell. The secondary cell group may comprise a second subset ofthe at least one secondary cell. Uplink transmissions by the wirelessdevice in the primary cell group may employ a first synchronizationsignal transmitted on the primary cell as a primary timing reference.Uplink transmissions in the secondary cell group may employ a secondsynchronization signal on an activated secondary cell of the secondarycell group as a secondary timing reference.

The at least one control message may cause in the wireless deviceconfiguration of a time alignment timer for each of the plurality ofcell groups. The time alignment timer may start or restart in responseto the wireless device receiving a timing advance command to adjustuplink transmission timing of a commanded cell group in the plurality ofcell groups. The commanded cell group may be considered: out-of-sync inresponse to the time alignment timer being expired or not running; andin-sync in response to the time alignment timer running. The wirelessdevice may configure the random access resources in response receivingthe at least one control message. The at least one control message maycomprise a plurality of random access resource parameters for thesecondary cell. The plurality of random access resource parameters maycomprise an index, a frequency offset, and a plurality of sequenceparameters.

The wireless device may initiate a random access process for a secondarycell in the secondary cell group in response to receiving a controlcommand at block 1302. The control command may comprise a mask index anda preamble identifier of a random access preamble. The control commandmay further comprise an index identifying the secondary cell if thecontrol command is not transmitted on the secondary cell. The wirelessdevice may transmit a first random access preamble on random accessresources of the secondary cell in response to the control command. Thewireless device may abort the random access process on the secondarycell if the primary cell group becomes out-of-sync at block 1305.

The wireless device may transmit, autonomously, a second random accesspreamble on the primary cell group to obtain uplink transmission timingof the primary cell group if the primary cell group becomes out-of-sync.The wireless device may receive a random access response on the primarycell from the base station. The wireless device may release the at leastone secondary cell if the primary cell group becomes out-of-sync. Thewireless device may ignore any message received in downlink controlchannels of each of the at least one secondary cell if the primary cellgroup becomes out-of-sync. The wireless device may stop monitoringdownlink control channels of each of the at least one secondary cell ifthe primary cell group becomes out-of-sync. The wireless device mayignore any timing advance command for the secondary cell group if theprimary cell group becomes out-of-sync.

According to some of the various aspects of embodiments, a wirelessdevice may be configured to communicate employing a plurality of cells.The wireless device may receive at least one control message from a basestation at block 1300. The at least one control message may cause in thewireless device configuration of a primary cell and at least onesecondary cell in the plurality of cells. The at least one controlmessage may cause in the wireless device assignment of each of the atleast one secondary cell to a cell group (implicitly or explicitly) in aplurality of cell groups. The plurality of cell groups may comprise aprimary cell group and a secondary cell group. The at least one controlmessage may cause in the wireless device configuration of a timealignment timer for each of the plurality of cell groups. The timealignment timer may start or restart in response to the wireless devicereceiving a timing advance command to adjust uplink transmission timingof a commanded cell group in the plurality of cell groups. The wirelessdevice may receive a control command initiating a random access processfor a secondary cell in the secondary cell group. The wireless devicemay abort the random access process on the secondary cell if a firsttime alignment timer of the primary cell group expires.

The aborting, by the wireless device, of the random access processcauses the wireless device: a) to stop transmission of a random accesspreamble for the random access process, if the random access preamblehas not yet been transmitted; and/or b) to stop monitoring for randomaccess responses corresponding to the random access preamble, if therandom access preamble has been transmitted.

According to some of the various aspects of embodiments, a base stationmay be configured to communicate employing a plurality of cells. Thebase station may transmit at least one control message to a wirelessdevice. The at least one control message may be configured to cause inthe wireless device configuration of a primary cell and at least onesecondary cell in the plurality of cells. The at least one controlmessage may be configured to cause assignment of a cell group index to asecondary cell. The cell group index may identify a cell group in aplurality of cell groups. The plurality of cell groups may comprise aprimary cell group and at least one secondary cell group. The primarycell group may comprise a first subset of the plurality of cells. Thefirst subset may comprise the primary cell. A secondary cell group inthe at least one secondary cell group may comprise a second subset ofthe at least one secondary cell. The at least one control message may beconfigured to cause configuration of a time alignment timer for eachcell group in the plurality of cell groups. Uplink signals transmittedby the wireless device in the primary cell group may employ a firstsynchronization signal transmitted on the primary cell as a first timingreference. Uplink signals transmitted by the wireless device in thesecondary cell group may employ a second synchronization signaltransmitted on one of at least one activated cell in the secondary cellgroup as a second timing reference.

The at least one control message may comprise a plurality of radiodedicated parameters for each one of the at least one secondary cell.The one secondary cell is assigned to one of the at least one secondarycell group identified by a second cell group index if the plurality ofradio dedicated parameters comprise the second cell group index for theone secondary cell. Otherwise, the one secondary cell assigned to theprimary cell group. The at least one control message comprises at leastone radio resource control message. The at least one control message isfurther configured to add or modify a radio bearer.

The at least one control message may comprise a plurality of mediaaccess control dedicated parameters. The plurality of media accesscontrol dedicated parameters may comprise: a time alignment timer valuefor the primary cell group and a sequence of at least one element. Eachelement may comprise one time alignment timer value and one cell groupindex. The one time alignment timer value may be associated with a cellgroup identified by the one cell group index. Each time alignment timervalue may be selected, by the base station, from a finite set ofpredetermined values. The plurality of media access control dedicatedparameters may be wireless device specific. The plurality of mediaaccess control dedicated parameters may comprise a deactivationparameter for the at least one secondary cell. The finite set ofpredetermined values may be eight. Each time alignment timer value maybe encoded employing three bits.

The base station may transmit a timing advance command. The timingadvance command may comprise a time adjustment value and a first cellgroup index. A first time alignment timer may correspond to a first cellgroup identified by the first cell group index starts or restarts inresponse to the base station successfully transmitting the timingadvance command to the wireless device. The timing advance command maycause substantial alignment of reception timing of uplink signals inframes and subframes of all one or more activated uplink carriers in thefirst cell group at the base station. The uplink signals are transmittedby the wireless device.

The first cell group may be considered out-of-sync in response to thefirst time alignment timer being expired or not running. The first cellgroup may be considered in-sync in response to the first time alignmenttimer running. The base station may transmit a control commandconfigured to cause transmission of a random access preamble on randomaccess resources of a first secondary cell in the first cell group. Thebase station may transmit a random access response on the primary cell.The random access response may comprise a second timing advance command,an uplink grant, and an index identifying the random access preamble.

According to some of the various aspects of embodiments, PDCCH order maybe used to trigger RACH for an activated SCell. For a newly configuredSCell or a configured but deactivated SCell, eNB may need to firstlyactivate the corresponding SCell and then trigger RACH on it. In anexample embodiment, with no retransmission of activation/deactivationcommand, activation of an SCell may need at least 8 ms, which may be anextra delay for UE to acquire the valid TA value on SCell compared tothe procedure on an already activated SCell. For a newly configuredSCell or a deactivated SCell, 8 ms may be required for SCell activation,and at least 6 ms may be required for preamble transmission, and atleast 4 ms may be required to receive the random access response. Atleast 18 ms may be required for a UE to get a valid TA. The possibledelay caused by retransmission or other configured parameters may needto be considered, e.g. the possible retransmission ofactivation/deactivation command, the time gap between when a RACH istriggered and when a preamble is transmitted (equal or larger than 6ms). The RAR may be transmitted within the RAR window (for example, 2ms, 10 ms, 50 ms), and possible retransmission of preamble may beconsidered. The delay for such a case may be more than 20 ms or even 30ms if retransmissions are considered. The delay values provided in thisparagraph are for an example scenario, and other values may apply to animplementation of random access process.

When time alignment timer of a secondary cell group expires, a PDCCHorder may initiate a random access process for the secondary cell tosynchronize the uplink timing of the active cells in the secondary cellgroup. This process may cause a relatively long delay until thesecondary cell group is synchronized. An embodiment may be required toreduce the time required to synchronize uplink of an out-of-syncsecondary cell group. In other word, a faster process may be needed tochange the state of a secondary cell group from out-of-sync to in-sync.

FIG. 14 is an example flow diagram illustrating uplink signal timingadvance processing as per an aspect of an embodiment of the presentinvention. According to some of the various aspects of embodiments, awireless device may be configured to communicate employing a pluralityof cells. The wireless device may receive at least one control messagefrom a base station at block 1400. The at least one control message maycause in the wireless device configuration of a primary cell and atleast one secondary cell in the plurality of cells. The at least onecontrol message may cause in the wireless device assignment of each ofthe at least one secondary cell to a cell group (implicitly orexplicitly) in a plurality of cell groups. The plurality of cell groupsmay comprise a primary cell group and a secondary cell group. Theprimary cell group may comprise a first subset of the plurality ofcells. The first subset may comprise the primary cell. The secondarycell group may comprise a second subset of the at least one secondarycell. In an example implementation, uplink transmissions by the wirelessdevice in the primary cell group may employ a first synchronizationsignal transmitted on the primary cell as a primary timing reference.Uplink transmissions in the secondary cell group may employ a secondsynchronization signal on an activated secondary cell of the secondarycell group as a secondary timing reference.

The at least one control message may comprise a plurality of mediaaccess control dedicated parameters. The plurality of media accesscontrol dedicated parameters may comprise a time alignment timer valuefor the primary cell group and a sequence of at least one element. Eachelement may comprise a time alignment timer value and a cell groupindex. The time alignment timer value may be associated with a cellgroup identified by a cell group index. Each time alignment timer valuemay be selected from a finite set of predetermined values. The at leastone control message may cause in the wireless device configuration of atime alignment timer for each of the plurality of cell groups. The timealignment timer may start or restart in response to the wireless devicereceiving a timing advance command to adjust a timing advance of acommanded cell group in the plurality of cell groups. Timing advancerefers to uplink transmission timing advance in a cell group.

When a secondary cell group is configured, it is initially in anout-of-sync state and its time alignment timer may not be running.Uplink transmission timing advance may be initialized as zero. A basestation may start a random access process to synchronize uplink timingof the wireless device for the secondary cell group. The base stationmay transmit a PDCCH order, and receive a random access preamble. Thebase station may then transmit a random access response including atiming advance command for the secondary cell group. The time alignmenttimer of the secondary cell group starts running and the secondary cellgroup may become in-sync after the wireless device receives andprocesses the random access response. In an example embodiment, a methodto initially synchronize the uplink transmission of a secondary cellgroup is initiating a random access process on the secondary cell group.

The secondary cell group may move to out-of-sync state, when the timealignment timer of the secondary cell group expires. To reduce the timerequired for changing the state of the secondary cell group fromout-of-state to in-sync, the wireless device may store the updatedtiming advance of the secondary cell group when the secondary cell groupbecomes out-of-sync. The stored value of the timing advance may not be aproper value of the uplink transmission timing advance when thesecondary cell group becomes in-sync again. Specially, when the wirelessdevice moves around, the propagation delay may change, for example,wireless devices may move to the coverage area of a repeater, and/or thelike. The value of the stored timing advance may be close the actualvalue of the timing advance for in-sync transmission of the wirelessdevice, especially when the cell radius is small and/or the wirelessdevice does not move, or moves slowly. In an example embodiment, thestored value of the timing advance may be employed in order to changethe state of the secondary cell group from out-of-sync to in-syncrelatively quickly and without initiating a random access process. Thisprocess may apply to the primary cell group, because when the primarycell becomes out-of-sync, the RRC layer in wireless device may initiatea radio link failure process.

According to some of the various aspects of embodiments, the wirelessdevice may generate a first updated timing advance by updating a firsttiming advance of the secondary cell group employing at least one firsttiming advance command for the secondary cell group at block 1402. Thefirst timing advance value is set to zero when the secondary cell groupis configured. The first timing advance value may be initiated by atiming advance value in a random access response for a random accesspreamble transmitted in the secondary cell group. The first timingadvance may be equal to a difference between received timing of thesecondary timing reference and transmission timing of the uplink signalsin the secondary cell group. The updating of the first timing advancemay further employ changes in a received downlink timing if the receiveddownlink timing changes are not compensated or are partly compensated bythe at least one timing advance command. A timing advance command in theat least one first timing advance command may comprise a timing advancecommand value and an index of the secondary cell group. The wirelessdevice maintains the value of the timing advance of the secondary cellgroup by applying the received timing advance commands and byautonomously changing the timing advance when required.

The wireless device may store the first updated timing advance uponexpiry of an associated time alignment timer of the secondary cell groupat block 1405. When the secondary cell group becomes out-of-sync, thewireless device may not change the timing advance value of the secondarycell group. The stored value of the first updated timing advance mayremain the same until the secondary cell group in wireless devicebecomes in-sync again. The stored value may be employed in order to movethe wireless device back to in-sync state again without initiating arandom access process. In an example embodiment, the stored value of thefirst timing advance may be released in the wireless device when thesecondary cell group is released.

The wireless device may receive a second timing advance command for thesecondary cell group with a timing advance value of zero at block 1407.The second timing advance command may cause starting the associated timealignment timer. The wireless device may change the secondary cell groupfrom an out-of-sync state to an in-sync state in response to the secondtiming advance command having a timing advance value of zero. In anexample embodiment, the wireless device may transmit a soundingreference signal in a cell in the secondary cell group in response toreceiving the second timing advance command if the at least one controlmessage configures regular transmission of the sounding reference signalon the cell. The base station may not have an accurate estimate of therequired uplink timing advance of the wireless device when the wirelessdevice is out-of-sync. Specially, if the wireless device moves from onearea to another area, its required timing advance may change. The basestation therefore, may transmit a timing advance command for thesecondary cell group with a timing advance value of zero. This mayquickly change the state of the secondary cell group to in-sync, withoutinitiating a random access process.

The wireless device may receive an uplink grant for an activated cell ofthe secondary cell group. The secondary cell group may be in in-syncstate now and the wireless device may be able to transmit uplinksignals. The wireless device may transmit uplink signals in radioresources identified in the uplink grant with a timing advance equal tothe stored first updated timing advance at block 1409. The base stationthen may receive uplink signals from the wireless device. Then if theuplink signal timing in the secondary cell requires adjustment, the basestation may transmit a timing advance command with a non-zero value toadjust uplink transmission timing in the secondary cell group and alignits timing with a reference timing in the base station.

The wireless device may receive a third timing advance command for thesecondary cell group subsequent to reception of the second timingadvance command when the associated time alignment timer is running. Thebase station may be able to measure received signal timing in thesecondary cell group and calculate the required time adjustment for theuplink signals in the secondary cell group. The third timing advancecommand may have a non-zero timing advance value. The third timingadvance command may restart the associated time alignment timer.

In an example embodiment, the wireless device may receive a timingadvance command for the secondary cell group subsequent to reception ofsaid second timing advance command and when the associated timealignment timer is running. In an example embodiment, the base stationmay transmit timing advance command(s) for the secondary cell group witha timing advance value of zero when the time alignment is running. Forexample, when the uplink signal timing in the secondary cell group issynchronized and does not require adjustment, and the time alignmenttimer of the secondary cell group is close to expiry. The base stationmay transmit a timing advance command for the secondary cell group witha timing advance value of zero. This may cause the wireless device andbase station restart the time alignment timer of the secondary cellgroup, and delay or prevent expiry of the associated time alignmenttimer. A timing advance command for a cell group may restart theassociated time alignment timer of the cell group.

According to some of the various aspects of embodiments, an SCellwithout an uplink may be assigned to a TAG (sTAG or pTAG). An eNB mayassign a TAG to the SCell without an uplink based on cell configurationparameters such as: cell downlink frequency, network deploymentconfigurations, and/or the like. For example, an SCell without an uplinkmay be grouped with other SCells in the same band. A TAG may have atleast one SCell with a configured uplink. Therefore, an SCell without anuplink may not be the only cell in a TAG. This may impose certainrequirements in network configuration, for example, an SCell without anuplink may not be the only cell in a band. In another example, an SCellwithout an uplink may not be the only cell that is going through asingle band repeater (therefore, may experience its own unique delay).It may be possible that an SCell without a configured uplink be selectedas the timing reference for the sTAG comprising the SCell. In anotherexample implementation, the requirement for a reference cell may bechanged in a way that only active SCells with a configured uplink may beselected as a timing reference.

For an SCell without an uplink, the eNB may not have timing informationabout the propagation delay for that SCell. An SCell without an uplinkmay not have any uplink transmission, such as a PUSCH, a preamble, anSRS, and/or the like. An eNB may rely on one of the following to selecta TAG for the SCell: the configuration parameters of the SCell, networkdeployment parameters, CSI feedback, a combination of these parameters,and/or the like. In an example embodiment, an sTAG may comprise at leastone cell with a configured downlink and configured uplink. The SCellwithout an uplink may be the only active SCell in a TAG, and thereforemay be the timing reference of the TAG.

According to some of the various aspects of embodiments, the UEtransceiver may use the reference cell of the sTAG to receive the SCelldownlink signal. Grouping an SCell without an uplink with a cell group,may allow the UE to employ the synchronization signal of the sTAG of theSCell for downlink subframe and frame reception. In an exampleembodiment, the TAG ID may not be a part of uplink parameters of anSCell configuration because SCells without an uplink do not compriseuplink parameters. SCells without an uplink may not include a RACH.Since the SCells without an uplink do not include other uplink channelssuch as an SRS or a PUSCH, the eNB may not be able to detect and monitorthe timing delay for the SCell without an uplink. The eNB may receiveuplink channel state information (CSI) and an ACK/NACK for an SCellwithout an uplink in the PCell PUCCH or UCI of other uplink packetstransmitted on PUSCH of other carriers.

According to some of the various aspects of embodiments, a wirelessdevice may be configured to communicate employing a plurality of cells.The wireless device may at least one control message from a basestation. The at least one control message may cause in the wirelessdevice configuration of a primary cell and a plurality of secondarycells in the plurality of cells. The plurality of cells consisting of: aplurality of downlink-uplink cells and at least one downlink-only cell.Each of the plurality of downlink-uplink cells may have a configureduplink and a configured downlink. Each of the at least one downlink-onlycell may have a configured downlink with no configured uplink.

The at least one control message may cause in the wireless deviceassignment of each of the plurality of secondary cells to a cell groupin a plurality of cell groups. The assignment may be done implicitly orexplicitly as described in this disclosure. The plurality of cell groupsmay comprise a primary cell group and at least one secondary cell group.A primary cell group may comprise a first subset of the plurality ofcells. The first subset may comprise the primary cell. A secondary cellgroup in the at least one secondary cell group may comprise a secondsubset of the plurality of secondary cells. Uplink signals transmittedby the wireless device in the primary cell group may employ a firstsynchronization signal transmitted on the primary cell as a first timingreference. Uplink signals transmitted by the wireless device in thesecondary cell group may employ a second synchronization signaltransmitted on one of at least one activated cell in the secondary cellgroup as a second timing reference. The primary cell may be adownlink-uplink cell.

The at least one control message may comprise a plurality of radiodedicated parameters for each one of the plurality of secondary cells.One secondary cell assigned to one of the at least one secondary cellgroup identified by a second cell group index if the plurality of radiodedicated parameters comprise the second cell group index for the onesecondary cell. Otherwise, the one secondary cell is assigned to theprimary cell group.

The at least one control message may further cause in the wirelessdevice configuration of a time alignment timer for each cell group inthe plurality of cell groups. The at least one control message maycomprise at least one radio resource control message. The at least onecontrol message may be further configured to add or modify a radiobearer. The at least one control message may comprise a time alignmenttimer parameter for each cell group in the plurality of cell groups.

The wireless device may receive at least one timing advance command fromthe base station. The timing advance command may comprise a timeadjustment value, and an index identifying a first cell group in theplurality of cell groups. The wireless device may apply the timingadvance command to uplink transmission timing of at least onedownlink-uplink cell in the first cell group. The timing advance commandmay cause substantial alignment of reception timing of uplink signalstransmitted by the wireless device in frames and subframes of one ormore activated downlink-uplink cells in the first cell group at the basestation.

Each cell group in the plurality of cell groups may comprise one or moreof the plurality of downlink-uplink cells. At least one of the one ormore downlink-uplink cells may be configured with a random accesschannel. Each of the at least one downlink-only cell may be assigned toa cell group comprising at least one of the plurality of downlink-uplinkcells in the same frequency band as the downlink-only cell. A frequencyband may comprise a plurality of frequency channels (carriers). Thewireless device may start or restart a first time alignment timercorresponding to the first cell group in response to the wireless devicereceiving the timing advance command.

The first cell group may be considered out-of-sync in response to thefirst time alignment timer being expired or not running. The first cellgroup may be considered in-sync in response to the first time alignmenttimer running. The wireless device may receive a control command causingtransmission of a random access preamble on random access resources of afirst secondary cell in the secondary cell group.

According to some of the various aspects of embodiments, the randomaccess procedure may be initiated by a PDCCH order or by the MACsublayer itself. Random access procedure on an SCell may be initiated bya PDCCH order. If a UE receives a PDCCH transmission consistent with aPDCCH order masked with its C-RNTI (radio network temporary identifier),and for a specific serving cell, the UE may initiate a random accessprocedure on this serving cell. For random access on the PCell a PDCCHorder or RRC optionally indicate the ra-PreambleIndex and thera-PRACH-MaskIndex; and for random access on an SCell, the PDCCH orderindicates the ra-PreambleIndex with a value different from zero and thera-PRACH-MaskIndex. For the pTAG preamble transmission on PRACH andreception of a PDCCH order may only be supported for PCell.

According to some of the various aspects of embodiments, the proceduremay use some of the following information: a) the available set of PRACHresources for the transmission of the random access preamble,prach-ConfigIndex, b) for PCell, the groups of random access preamblesand/or the set of available random access preambles in each group, c)for PCell, the preambles that are contained in random access preamblesgroup A and Random Access Preambles group B are calculated, d) the RAresponse window size ra-ResponseWindowSize, e) the power-ramping factorpowerRampingStep, f) the maximum number of preamble transmissionpreambleTransMax, g) the initial preamble powerpreambleInitialReceivedTargetPower, h) the preamble format based offsetDELTA_PREAMBLE, i) for PCell, the maximum number of Msg3 HARQtransmissions maxHARQ-Msg3Tx, j) for PCell, the Contention ResolutionTimer mac-ContentionResolutionTimer. These parameters may be updatedfrom upper layers before each Random Access procedure is initiated.

According to some of the various aspects of embodiments, the RandomAccess procedure may be performed as follows: Flush the Msg3 buffer; setthe PREAMBLE_TRANSMISSION_COUNTER to 1; set the backoff parameter valuein the UE to 0 ms; for the RN (relay node), suspend any RN subframeconfiguration; proceed to the selection of the Random Access Resource.There may be one Random Access procedure ongoing at any point in time.If the UE receives a request for a new Random Access procedure whileanother is already ongoing, it may be up to UE implementation whether tocontinue with the ongoing procedure or start with the new procedure.

According to some of the various aspects of embodiments, the RandomAccess Resource selection procedure may be performed as follows. Ifra-PreambleIndex (Random Access Preamble) and ra-PRACH-MaskIndex (PRACHMask Index) have been explicitly signalled and ra-PreambleIndex is notzero, then the Random Access Preamble and the PRACH Mask Index may bethose explicitly signalled. Otherwise, the Random Access Preamble may beselected by the UE.

The UE may determine the next available subframe containing PRACHpermitted by the restrictions given by the prach-ConfigIndex, the PRACHMask Index and physical layer timing requirements (a UE may take intoaccount the possible occurrence of measurement gaps when determining thenext available PRACH subframe). If the transmission mode is TDD and thePRACH Mask Index is equal to zero, then if ra-PreambleIndex wasexplicitly signalled and it was not 0 (i.e., not selected by MAC), thenrandomly select, with equal probability, one PRACH from the PRACHsavailable in the determined subframe. Else, the UE may randomly select,with equal probability, one PRACH from the PRACHs available in thedetermined subframe and the next two consecutive subframes. If thetransmission mode is not TDD or the PRACH Mask Index is not equal tozero, a UE may determine a PRACH within the determined subframe inaccordance with the requirements of the PRACH Mask Index. Then the UEmay proceed to the transmission of the Random Access Preamble.

PRACH mask index values may range for example from 0 to 16. PRACH maskindex value may determine the allowed PRACH resource index that may beused for transmission. For example, PRACH mask index 0 may mean that allPRACH resource indeces are allowed; or PRACH mask index 1 may mean thatPRACH resource index 0 may be used. PRACH mask index may have differentmeaning in TDD and FDD systems.

The random-access procedure may be performed by UE settingPREAMBLE_RECEIVED_TARGET_POWER topreambleInitialReceivedTargetPower+DELTA_PREAMBLE+(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep.The UE may instruct the physical layer to transmit a preamble using theselected PRACH, corresponding RA-RNTI, preamble index andPREAMBLE_RECEIVED_TARGET_POWER.

According to some of the various aspects of embodiments, once the randomaccess preamble is transmitted and regardless of the possible occurrenceof a measurement gap, the UE may monitor the PDCCH of the PCell forrandom access response(s) identified by the RA-RNTI (random access radionetwork identifier) a specific RA-RNTI defined below, in the randomaccess response (RAR) window which may start at the subframe thatcontains the end of the preamble transmission plus three subframes andhas length ra-ResponseWindowSize subframes. The specific RA-RNTIassociated with the PRACH in which the Random Access Preamble istransmitted, is computed as: RA-RNTI=1+t_id+10*f_id. Where t_id may bethe index of the first subframe of the specified PRACH (0≦t_id<10), andf_id is the index of the specified PRACH within that subframe, inascending order of frequency domain (0≦f_id<6). The UE may stopmonitoring for RAR(s) after successful reception of a RAR containingrandom access preamble identifiers that matches the transmitted randomaccess preamble.

According to some of the various aspects of embodiments, if a downlinkassignment for this TTI (transmission tme interval) has been received onthe PDCCH for the RA-RNTI and the received TB (transport block) issuccessfully decoded, the UE may regardless of the possible occurrenceof a measurement gap: if the RAR contains a backoff indicator (BI)subheader, set the backoff parameter value in the UE employing the BIfield of the backoff indicator subheader, else, set the backoffparameter value in the UE to zero ms. If the RAR contains a randomaccess preamble identifier corresponding to the transmitted randomaccess preamble, the UE may consider this RAR reception successful andapply the following actions for the serving cell where the random accesspreamble was transmitted: process the received riming advance commandfor the cell group in which the preamble was transmitted, indicate thepreambleInitialReceivedTargetPower and the amount of power rampingapplied to the latest preamble transmission to lower layers (i.e.,(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep); process thereceived uplink grant value and indicate it to the lower layers; theuplink grant is applicable to uplink of the cell in which the preamblewas transmitted. If ra-PreambleIndex was explicitly signalled and it wasnot zero (e.g., not selected by MAC), consider the random accessprocedure successfully completed. Otherwise, if the Random AccessPreamble was selected by UE MAC, set the Temporary C-RNTI to the valuereceived in the RAR message. When an uplink transmission is required,e.g., for contention resolution, the eNB may not provide a grant smallerthan 56 bits in the Random Access Response.

According to some of the various aspects of embodiments, if no RAR isreceived within the RAR window, or if none of all received RAR containsa random access preamble identifier corresponding to the transmittedrandom access preamble, the random access response reception mayconsidered not successful. If RAR is not received, UE may incrementPREAMBLE_TRANSMISSION_COUNTER by 1. IfPREAMBLE_TRANSMISSION_COUNTER=preambleTransMax+1 and random accesspreamble is transmitted on the PCell, then UE may indicate a randomaccess problem to upper layers (RRC). This may result in radio linkfailure. If PREAMBLE_TRANSMISSION_COUNTER=preambleTransMax+1 and therandom access preamble is transmitted on an SCell, then UE may considerthe random access procedure unsuccessfully completed. UE may stay in RRCconnected mode and keep the RRC connection active even though a randomaccess procedure unsuccessfully completed on a secondary TAG. Accordingto some of the various aspects of embodiments, at completion of therandom access procedure, the UE may discard explicitly signalledra-PreambleIndex and ra-PRACH-MaskIndex, if any; and flush the HARQbuffer used for transmission of the MAC PDU in the Msg3 buffer. Inaddition, the RN may resume the suspended RN subframe configuration, ifany.

According to some of the various aspects of embodiments, a UE may have aconfigurable timer timeAlignmentTimer per TAG. The timeAlignmentTimer isused to control how long the UE considers the Serving Cells belonging tothe associated TAG to be uplink time aligned (in-sync). When a TimingAdvance Command MAC control element is received, the UE may apply theriming advance command for the indicated TAG, and start or restart thetimeAlignmentTimer associated with the indicated TAG. When a timingadvance command is received in a RAR message for a serving cellbelonging to a TAG and if the random access preamble was not selected byUE MAC, the UE may apply the timing advance command for this TAG, andmay start or restart the timeAlignmentTimer associated with this TAG.When a timeAlignmentTimer associated with the pTAG expires, the UE may:flush all HARQ buffers for all serving cells; notify RRC to releasePUCCH/SRS for all serving cells; clear any configured downlinkassignments and uplink grants; and consider all runningtimeAlignmentTimers as expired. When a timeAlignmentTimer associatedwith an sTAG expires, then for all Serving Cells belonging to this TAG,the UE may flush all HARQ buffers; and notify RRC to release SRS. The UEmay not perform any uplink transmission on a serving Cell except therandom access preamble transmission when the timeAlignmentTimerassociated with the TAG to which this serving cell belongs is notrunning. When the timeAlignmentTimer associated with the pTAG is notrunning, the UE may not perform any uplink transmission on any servingcell except the random access preamble transmission on the PCell. A UEstores or maintains N_TA (current timing advance value of an sTAG) uponexpiry of associated timeAlignmentTimer. The UE may apply a receivedtiming advance command MAC control element and starts associatedtimeAlignmentTimer. Transmission of the uplink radio frame number i fromthe UE may start (N_(TA)+N_(TA offset))×T_(s) seconds before the startof the corresponding downlink radio frame at the UE, where0≦N_(TA)≦20512. In an example implementation, N_(TA offset)=0 for framestructure type 1 (FDD) and N_(TA offset)=624 for frame structure type 2(TDD).

According to some of the various aspects of embodiments, upon receptionof a timing advance command for a TAG containing the primary cell, theUE may adjust uplink transmission timing for PUCCH/PUSCH/SRS of theprimary cell based on the received timing advance command. The ULtransmission timing for PUSCH/SRS of a secondary cell may be the same asthe primary cell if the secondary cell and the primary cell belong tothe same TAG. Upon reception of a timing advance command for a TAG notcontaining the primary cell, the UE may adjust uplink transmissiontiming for PUSCH/SRS of secondary cells in the TAG based on the receivedtiming advance command where the UL transmission timing for PUSCH/SRS isthe same for all the secondary cells in the TAG.

The timing advance command for a TAG may indicates the change of theuplink timing relative to the current uplink timing for the TAG asmultiples of 16Ts (Ts: sampling time unit). The start timing of therandom access preamble may obtained employing a downlink synchronizationtime in the same TAG. In case of random access response, an 11-bittiming advance command, TA, for a TAG may indicate NTA values by indexvalues of TA=0, 1, 2, . . . , 1282, where an amount of the timealignment for the TAG may be given by NTA=TA×16. In other cases, a 6-bittiming advance command, TA, for a TAG may indicate adjustment of thecurrent NTA value, NTA,old, to the new NTA value, NTA,new, by indexvalues of TA=0, 1, 2, . . . , 63, where NTA,new=NTA,old+(TA−31)×16.Here, adjustment of NTA value by a positive or a negative amountindicates advancing or delaying the uplink transmission timing for theTAG by a given amount respectively. For a timing advance commandreceived on subframe n, the corresponding adjustment of the uplinktransmission timing may apply from the beginning of subframe n+6. Forserving cells in the same TAG, when the UE's uplink PUCCH/PUSCH/SRStransmissions in subframe n and subframe n+1 are overlapped due to thetiming adjustment, the UE may complete transmission of subframe n andnot transmit the overlapped part of subframe n+1. If the receiveddownlink timing changes and is not compensated or is only partlycompensated by the uplink timing adjustment without timing advancecommand, the UE may change NTA accordingly.

Downlink frames and subframes of downlink carriers may be time aligned(by the base station) in carrier aggregation and multiple TAGconfiguration. Time alignment errors may be tolerated to some extend.For example, for intra-band contiguous carrier aggregation, timealignment error may not exceed 130 ns. In another example, forintra-band non-contiguous carrier aggregation, time alignment error maynot exceed 260 ns. In another example, for inter-band carrieraggregation, time alignment error may not exceed 1.3 μs.

The UE may have capability to follow the frame timing change of theconnected base station. The uplink frame transmission may take place(N_(TA)+N_(TA offset))×T_(s) before the reception of the first detectedpath (in time) of the corresponding downlink frame from the referencecell. The UE may be configured with a pTAG containing the PCell. ThepTAG may also contain one or more SCells, if configured. The UE may alsobe configured with one or more sTAGs, in which case the pTAG may containone PCell and the sTAG may contain at least one SCell with configureduplink. In pTAG, UE may use the PCell as the reference cell for derivingthe UE transmit timing for cells in the pTAG. The UE may employ asynchronization signal on the reference cell to drive downlink timing.When a UE is configured with an sTAG, the UE may use an activated SCellfrom the sTAG for deriving the UE transmit timing for cell in the sTAG.

In at least one of the various embodiments, uplink physical channel(s)may correspond to a set of resource elements carrying informationoriginating from higher layers. The following example uplink physicalchannel(s) may be defined for uplink: a) Physical Uplink Shared Channel(PUSCH), b) Physical Uplink Control Channel (PUCCH), c) Physical RandomAccess Channel (PRACH), and/or the like. Uplink physical signal(s) maybe used by the physical layer and may not carry information originatingfrom higher layers. For example, reference signal(s) may be consideredas uplink physical signal(s). Transmitted signal(s) in slot(s) may bedescribed by one or several resource grids including, for example,subcarriers and SC-FDMA or OFDMA symbols. Antenna port(s) may be definedsuch that the channel over which symbol(s) on antenna port(s) may beconveyed and/or inferred from the channel over which other symbol(s) onthe same antenna port(s) is/are conveyed. There may be one resource gridper antenna port. The antenna port(s) used for transmission of physicalchannel(s) or signal(s) may depend on the number of antenna port(s)configured for the physical channel(s) or signal(s).

According to some of the various embodiments, physical downlink controlchannel(s) may carry transport format, scheduling assignments, uplinkpower control, and other control information. PDCCH may support multipleformats. Multiple PDCCH packets may be transmitted in a subframe.According to some of the various embodiments, scheduling controlpacket(s) may be transmitted for packet(s) or group(s) of packetstransmitted in downlink shared channel(s). Scheduling control packet(s)may include information about subcarriers used for packettransmission(s). PDCCH may also provide power control commands foruplink channels. PDCCH channel(s) may carry a plurality of downlinkcontrol packets in subframe(s). Enhance PDCCH may be implemented in acell as an option to carrier control information. According to some ofthe various embodiments, PHICH may carry the hybrid-ARQ (automaticrepeat request) ACK/NACK.

Other arrangements for PCFICH, PHICH, PDCCH, enhanced PDCCH, and/orPDSCH may be supported. The configurations presented here are forexample purposes. In another example, resources PCFICH, PHICH, and/orPDCCH radio resources may be transmitted in radio resources including asubset of subcarriers and pre-defined time duration in each or some ofthe subframes. In an example, PUSCH resource(s) may start from the firstsymbol. In another example embodiment, radio resource configuration(s)for PUSCH, PUCCH, and/or PRACH (physical random access channel) may usea different configuration. For example, channels may be timemultiplexed, or time/frequency multiplexed when mapped to uplink radioresources.

According to some of the various aspects of embodiments, the physicallayer random access preamble may comprise a cyclic prefix of length Tcpand a sequence part of length Tseq. The parameter values may bepre-defined and depend on the frame structure and a random accessconfiguration. In an example embodiment, Tcp may be 0.1 msec, and Tseqmay be 0.9 msec. Higher layers may control the preamble format. Thetransmission of a random access preamble, if triggered by the MAC layer,may be restricted to certain time and frequency resources. The start ofa random access preamble may be aligned with the start of thecorresponding uplink subframe at a wireless device with N_TA=0.

According to an example embodiment, random access preambles may begenerated from Zadoff-Chu sequences with a zero correlation zone,generated from one or several root Zadoff-Chu sequences. In anotherexample embodiment, the preambles may also be generated using otherrandom sequences such as Gold sequences. The network may configure theset of preamble sequences a wireless device may be allowed to use.According to some of the various aspects of embodiments, there may be amultitude of preambles (e.g. 64) available in cell(s). From the physicallayer perspective, the physical layer random access procedure mayinclude the transmission of random access preamble(s) and random accessresponse(s). Remaining message(s) may be scheduled for transmission by ahigher layer on the shared data channel and may not be considered partof the physical layer random access procedure. For example, a randomaccess channel may occupy 6 resource blocks in a subframe or set ofconsecutive subframes reserved for random access preamble transmissions.

According to some of the various embodiments, the following actions maybe followed for a physical random access procedure: 1) layer 1 proceduremay be triggered upon request of a preamble transmission by higherlayers; 2) a preamble index, a target preamble received power, acorresponding RA-RNTI (random access-radio network temporary identifier)and/or a PRACH resource may be indicated by higher layers as part of arequest; 3) a preamble transmission power P_PRACH may be determined; 4)a preamble sequence may be selected from the preamble sequence set usingthe preamble index; 5) a single preamble may be transmitted usingselected preamble sequence(s) with transmission power P_PRACH on theindicated PRACH resource; 6) detection of a PDCCH with the indicated RARmay be attempted during a window controlled by higher layers; and/or thelike. If detected, the corresponding downlink shared channel transportblock may be passed to higher layers. The higher layers may parsetransport block(s) and/or indicate an uplink grant to the physicallayer(s).

Before a wireless device initiates transmission of a random accesspreamble, it may access one or many of the following types ofinformation: a) available set(s) of PRACH resources for the transmissionof a random access preamble; b) group(s) of random access preambles andset(s) of available random access preambles in group(s); c) randomaccess response window size(s); d) power-ramping factor(s); e) maximumnumber(s) of preamble transmission(s); f) initial preamble power; g)preamble format based offset(s); h) contention resolution timer(s);and/or the like. These parameters may be updated from upper layers ormay be received from the base station before random access procedure(s)may be initiated.

According to some of the various aspects of embodiments, a wirelessdevice may select a random access preamble using available information.The preamble may be signaled by a base station or the preamble may berandomly selected by the wireless device. The wireless device maydetermine the next available subframe containing PRACH permitted byrestrictions given by the base station and the physical layer timingrequirements for TDD or FDD. Subframe timing and the timing oftransmitting the random access preamble may be determined based, atleast in part, on synchronization signals received from the base stationand/or the information received from the base station. The wirelessdevice may proceed to the transmission of the random access preamblewhen it has determined the timing. The random access preamble may betransmitted on a second plurality of subcarriers on the first uplinkcarrier.

According to some of the various aspects of embodiments, once a randomaccess preamble is transmitted, a wireless device may monitor the PDCCHof a primary carrier for random access response(s), in a random accessresponse window. There may be a pre-known identifier in PDCCH thatidentifies a random access response. The wireless device may stopmonitoring for random access response(s) after successful reception of arandom access response containing random access preamble identifiersthat matches the transmitted random access preamble and/or a randomaccess response address to a wireless device identifier. A base stationrandom access response may include a time alignment command. Thewireless device may process the received time alignment command and mayadjust its uplink transmission timing according the time alignment valuein the command. For example, in a random access response, a timealignment command may be coded using 11 bits, where an amount of thetime alignment may be based on the value in the command. In an exampleembodiment, when an uplink transmission is required, the base stationmay provide the wireless device a grant for uplink transmission.

If no random access response is received within the random accessresponse window, and/or if none of the received random access responsescontains a random access preamble identifier corresponding to thetransmitted random access preamble, the random access response receptionmay be considered unsuccessful and the wireless device may, based on thebackoff parameter in the wireless device, select a random backoff timeand delay the subsequent random access transmission by the backoff time,and may retransmit another random access preamble.

According to some of the various aspects of embodiments, a wirelessdevice may transmit packets on an uplink carrier. Uplink packettransmission timing may be calculated in the wireless device using thetiming of synchronization signal(s) received in a downlink. Uponreception of a timing alignment command by the wireless device, thewireless device may adjust its uplink transmission timing. The timingalignment command may indicate the change of the uplink timing relativeto the current uplink timing. The uplink transmission timing for anuplink carrier may be determined using time alignment commands and/ordownlink reference signals.

According to some of the various aspects of embodiments, a timealignment command may indicate timing adjustment for transmission ofsignals on uplink carriers. For example, a time alignment command mayuse 6 bits. Adjustment of the uplink timing by a positive or a negativeamount indicates advancing or delaying the uplink transmission timing bya given amount respectively.

For a timing alignment command received on subframe n, the correspondingadjustment of the timing may be applied with some delay, for example, itmay be applied from the beginning of subframe n+6. When the wirelessdevice's uplink transmissions in subframe n and subframe n+1 areoverlapped due to the timing adjustment, the wireless device maytransmit complete subframe n and may not transmit the overlapped part ofsubframe n+1.

According to some of the various aspects of embodiments, a wirelessdevice may be preconfigured with one or more carriers. When the wirelessdevice is configured with more than one carrier, the base station and/orwireless device may activate and/or deactivate the configured carriers.One of the carriers (the primary carrier) may always be activated. Othercarriers may be deactivated by default and/or may be activated by a basestation when needed. A base station may activate and deactivate carriersby sending an activation/deactivation MAC control element. Furthermore,the UE may maintain a carrier deactivation timer per configured carrierand deactivate the associated carrier upon its expiry. The same initialtimer value may apply to instance(s) of the carrier deactivation timer.The initial value of the timer may be configured by a network. Theconfigured carriers (unless the primary carrier) may be initiallydeactivated upon addition and after a handover.

According to some of the various aspects of embodiments, if a wirelessdevice receives an activation/deactivation MAC control elementactivating the carrier, the wireless device may activate the carrier,and/or may apply normal carrier operation including: sounding referencesignal transmissions on the carrier (if the carrier is uplink timealigned), CQI (channel quality indicator)/PMI (precoding matrixindicator)/RI (ranking indicator) reporting for the carrier, PDCCHmonitoring on the carrier, PDCCH monitoring for the carrier, start orrestart the carrier deactivation timer associated with the carrier,and/or the like. If the device receives an activation/deactivation MACcontrol element deactivating the carrier, and/or if the carrierdeactivation timer associated with the activated carrier expires, thebase station or device may deactivate the carrier, and may stop thecarrier deactivation timer associated with the carrier, and/or may flushHARQ buffers associated with the carrier.

If PDCCH on a carrier scheduling the activated carrier indicates anuplink grant or a downlink assignment for the activated carrier, thedevice may restart the carrier deactivation timer associated with thecarrier. When a carrier is deactivated, the wireless device may nottransmit SRS (sounding reference signal) for the carrier, may not reportCQI/PMI/RI for the carrier, may not transmit on UL-SCH for the carrier,may not monitor the PDCCH on the carrier, and/or may not monitor thePDCCH for the carrier.

In this specification, “a” and “an” and similar phrases are to beinterpreted as “at least one” and “one or more.” In this specification,the term “may” is to be interpreted as “may, for example,” In otherwords, the term “may” is indicative that the phrase following the term“may” is an example of one of a multitude of suitable possibilities thatmay, or may not, be employed to one or more of the various embodiments.If A and B are sets and every element of A is also an element of B, A iscalled a subset of B. In this specification, only non-empty sets andsubsets are considered. For example, possible subsets of B={cell1,cell2} are: {cell1}, {cell2}, and {cell1, cell2}.

In this specification, parameters (Information elements: IEs) maycomprise one or more objects, and each of those objects may comprise oneor more other objects. For example, if parameter (IE) N comprisesparameter (IE) M, and parameter (IE) M comprises parameter (IE) K, andparameter (IE) K comprises parameter (information element) J, then, forexample, N comprises K, and N comprises J.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an isolatableelement that performs a defined function and has a defined interface toother elements. The modules described in this disclosure may beimplemented in hardware, software in combination with hardware,firmware, wetware (i.e hardware with a biological element) or acombination thereof, all of which are behaviorally equivalent. Forexample, modules may be implemented as a software routine written in acomputer language configured to be executed by a hardware machine (suchas C, C++, Fortran, Java, Basic, Matlab or the like) or amodeling/simulation program such as Simulink, Stateflow, GNU Octave, orLabVIEWMathScript. Additionally, it may be possible to implement modulesusing physical hardware that incorporates discrete or programmableanalog, digital and/or quantum hardware. Examples of programmablehardware comprise: computers, microcontrollers, microprocessors,application-specific integrated circuits (ASICs); field programmablegate arrays (FPGAs); and complex programmable logic devices (CPLDs).Computers, microcontrollers and microprocessors are programmed usinglanguages such as assembly, C, C++ or the like. FPGAs, ASICs and CPLDsare often programmed using hardware description languages (HDL) such asVHSIC hardware description language (VHDL) or Verilog that configureconnections between internal hardware modules with lesser functionalityon a programmable device. Finally, it needs to be emphasized that theabove mentioned technologies are often used in combination to achievethe result of a functional module.

The disclosure of this patent document incorporates material which issubject to copyright protection. The copyright owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and Trademark Officepatent file or records, for the limited purposes required by law, butotherwise reserves all copyright rights whatsoever.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example, and notlimitation. It will be apparent to persons skilled in the relevantart(s) that various changes in form and detail can be made thereinwithout departing from the spirit and scope. In fact, after reading theabove description, it will be apparent to one skilled in the relevantart(s) how to implement alternative embodiments. Thus, the presentembodiments should not be limited by any of the above describedexemplary embodiments. In particular, it should be noted that, forexample purposes, the above explanation has focused on the example(s)using FDD communication systems. However, one skilled in the art willrecognize that embodiments of the invention may also be implemented inTDD communication systems. The disclosed methods and systems may beimplemented in wireless or wireline systems. The features of variousembodiments presented in this invention may be combined. One or manyfeatures (method or system) of one embodiment may be implemented inother embodiments. Only a limited number of example combinations areshown to indicate to one skilled in the art the possibility of featuresthat may be combined in various embodiments to create enhancedtransmission and reception systems and methods.

In addition, it should be understood that any figures which highlightthe functionality and advantages, are presented for example purposesonly. The disclosed architecture is sufficiently flexible andconfigurable, such that it may be utilized in ways other than thatshown. For example, the actions listed in any flowchart may bere-ordered or only optionally used in some embodiments.

Further, the purpose of the Abstract of the Disclosure is to enable theU.S. Patent and Trademark Office and the public generally, andespecially the scientists, engineers and practitioners in the art whoare not familiar with patent or legal terms or phraseology, to determinequickly from a cursory inspection the nature and essence of thetechnical disclosure of the application. The Abstract of the Disclosureis not intended to be limiting as to the scope in any way.

Finally, it is the applicant's intent that only claims that include theexpress language “means for” or “step for” be interpreted under 35U.S.C. 112, paragraph 6. Claims that do not expressly include the phrase“means for” or “step for” are not to be interpreted under 35 U.S.C. 112,paragraph 6.

What is claimed is:
 1. A method comprising: a) receiving, by a wirelessdevice to communicate employing a plurality of cells, at least onecontrol message from a base station, said at least one control messagecausing in said wireless device: i) configuration of a primary cell andat least one secondary cell in said plurality of cells; and ii)assignment of each of said at least one secondary cell to a cell groupin a plurality of cell groups, said plurality of cell groups comprising:(1) a primary cell group comprising a first subset of said plurality ofcells, said first subset comprising said primary cell, uplinktransmissions by said wireless device in said primary cell groupemploying a first synchronization signal transmitted on said primarycell as a primary timing reference; and (2) at least one secondary cellgroup, a secondary cell group in said at least one secondary cell groupcomprising a second subset of said at least one secondary cell, uplinktransmissions in said secondary cell group employing a secondsynchronization signal on an activated secondary cell of said secondarycell group as a secondary timing reference; b) initiating, by saidwireless device, a first random access process on a first uplink carrierof a first cell in said plurality of cells in response to receiving afirst control command; c) receiving, by said wireless device, a secondcontrol command for transmission of a second random access preamble on asecond uplink carrier of a second cell in said plurality of cells whilesaid first random access process is on-going, said second cell beingdifferent from said first cell; and d) determining, by said wirelessdevice, employing a pre-defined rule: i) to continue with said firstrandom access process and ignore said second control command; or ii) toabort said first random access process and to transmit said secondrandom access preamble.
 2. The method of claim 1, wherein saidpre-defined rule determines to continue with said first random accessprocess if: a) said first cell is said primary cell; and b) said secondcell is a secondary cell in said secondary cell group.
 3. The method ofclaim 1, wherein said pre-defined rule determines to continue with saidfirst random access process if: a) said first cell is a secondary cellin said secondary cell group; and b) said second cell is said primarycell.
 4. The method of claim 1, wherein said pre-defined rule determinesto continue with said first random access process and ignore said secondcontrol command.
 5. The method of claim 1, wherein said at least onecontrol message is configured to further cause in said wireless deviceconfiguration of a time alignment timer for each of said plurality ofcell groups, said time alignment timer starting or restarting inresponse to said wireless device receiving a timing advance command toadjust uplink transmission timing of a commanded cell group in saidplurality of cell groups.
 6. The method of claim 1, wherein said firstcontrol command comprises: a) a mask index; and b) a preamble identifierof a random access preamble.
 7. The method of claim 1, wherein saidfirst control command further comprises an index identifying said firstcell only if said control command is not transmitted on said first cell.8. The method of claim 1, wherein said first control command furthercomprises an index identifying said first cell only if said controlcommand is not transmitted on said first cell.
 9. The method of claim 1,wherein said at least one control message further causes in saidwireless device configuration of random access resources for said firstcell and said second cell.
 10. The method of claim 1, wherein said atleast one control message comprises a plurality of common parameters forsaid first cell and said second cell, said plurality of commonparameters comprising: a) a first plurality of random access resourceparameters identifying first random access resources for said firstcell; and b) a second plurality of random access resource parametersidentifying second random access resources for said second cell.
 11. Amethod comprising: a) receiving, by a wireless device to communicateemploying a plurality of cells, at least one control message from a basestation, said at least one control message causing in said wirelessdevice: i) configuration of a primary cell and at least one secondarycell in said plurality of cells; and ii) assignment of each of said atleast one secondary cell to a cell group in a plurality of cell groups,said plurality of cell groups comprising: (1) a primary cell groupcomprising a first subset of said plurality of cells, said first subsetcomprising said primary cell; and (2) at least one secondary cell group,a secondary cell group in said at least one secondary cell groupcomprising a second subset of said at least one secondary cell; b)initiating, by said wireless device, a first random access process on afirst uplink carrier of a first cell in said plurality of cells inresponse to receiving a first control command; c) receiving, by saidwireless device, a second control command for transmission of a secondrandom access preamble on a second uplink carrier of a second cell insaid plurality of cells while said first random access process ison-going; and d) determining, by said wireless device, employing apre-defined rule: iii) to continue with said first random access processand ignore said second control command; or iv) to abort said firstrandom access process and to transmit said second random accesspreamble.
 12. The method of claim 11, wherein said pre-defined ruledetermines to abort said first random access process if: a) said firstcell is said primary cell; and b) said second cell is a secondary cellin said secondary cell group.
 13. The method of claim 11, wherein saidpre-defined rule determines to abort said first random access processand to transmit said second random access preamble.
 14. The method ofclaim 11, wherein said first control command comprises: a) a mask index;and b) a preamble identifier of a random access preamble.
 15. A wirelessdevice comprising: a) one or more communication interfaces; b) one ormore processors; and c) memory storing instructions that, when executed,cause said wireless device to: i) receive at least one control messagefrom a base station, said at least one control message causing in saidwireless device: (1) configuration a plurality of cells comprising aprimary cell and at least one secondary cell in; and (2) assignment ofeach of said at least one secondary cell to a cell group in a pluralityof cell groups, said plurality of cell groups comprising: (a) a primarycell group comprising a first subset of said plurality of cells, saidfirst subset comprising said primary cell; and (b) at least onesecondary cell group, a secondary cell group in said at least onesecondary cell group comprising a second subset of said at least onesecondary cell; ii) initiate a first random access process on a firstuplink carrier of a first cell in said plurality of cells in response toreceiving a first control command; iii) receive a second control commandfor transmission of a second random access preamble on a second uplinkcarrier of a second cell in said plurality of cells while said firstrandom access process is on-going; and iv) determine employing apre-defined rule: (1) to continue with said first random access processand ignore said second control command; or (2) to abort said firstrandom access process and to transmit said second random accesspreamble.
 16. The wireless device of claim 15, wherein said pre-definedrule determines: a) to continue with said first random access process ifsaid first random access preamble is transmitted before reception ofsaid second control command; and b) to abort said first random accessprocess if said second control command is received before transmissionof said first random access preamble.
 17. The wireless device of claim15, wherein said pre-defined rule determines to abort said first randomaccess process if: a) said first cell is a secondary cell in saidsecondary cell group; and b) said second cell is said primary cell. 18.The wireless device of claim 15, wherein said first control commandcomprises: a) a mask index; and b) a preamble identifier of a randomaccess preamble.
 19. The wireless device of claim 15, wherein said atleast one control message comprises a plurality of common parameters forsaid first cell and said second cell, said plurality of commonparameters comprising: a) a first plurality of random access resourceparameters identifying first random access resources for said firstcell; and b) a second plurality of random access resource parametersidentifying second random access resources for said second cell.
 20. Thewireless device of claim 15, wherein said at least one control messagefurther causes in said wireless device configuration of random accessresources for said first cell and said second cell.